Method for Synthesizing Solids Such as Diamond and Products Produced Thereby

This invention was made with government support under Contract No.

N00019-91-J-4023 awarded by the Defense Advanced Research Projects Agency (DARPA). The Government has certain rights in the invention.

Cross Reference to Related Patent Applications This patent application is a continuation-in-part application of a patent application filed on August 27, 1993, entitled "A Method for Synthesizing Solids Such as Diamond and Products Produced Thereby", and which was filed in the names of Rustum Roy et al., which in turn is a continuation-in-part of an application filed on October 19, 1992, entitle "A Method for Synthesizing Solids Such as Diamond and Products Produced Thereby", and which was filed in the names of Rustum Roy et al., which in turn is a continuation-in-part application of U.S. Patent Application Serial No. 07/962,423, filed on October 16, 1992, entitled "A Method for Synthesizing Solids Such as Diamond and Products Produced Thereby", and which was filed in the names of Rustum Roy et al., and now abandoned, whi in turn is a continuation-in-part application of U.S. Patent Application Serial No. 07/955,956, filed October 2, 1992, entitled "A method for Synthesizing Solids Such as Diamond and Products Produced Thereby", filed in the name of Rustum Roy, and now abandoned.

Technical Field

The present invention relates generally to methods for the synthesis of various solids such as diamonds, diamond films, boron nitride and othe similar materials. This invention specifically relates to utilizing novel sources of reaction species (e.g., in the case of diamond formation, novel sources of carbon and/or hydrogen and/or seeds) for the manufacture of

various materials and the use of such materials for various commercial purposes.

Background Art There are various known methods for producing synthetic diamond. In first method, diamond grit may be synthesized by precipitating diamond fr carbon contained within a metal solution at high temperatures (e.g., 1400 ^β C) and high pressures (e.g., 60kbar). The resulting diamond which i produced at these high temperatures and high pressures may be free of second phase inclusions, but generally contains significant concentration of dissolved nitrogen and metal (e.g., nickel, iron, cobalt, etc.).

In a second technique, diamond powder may be produced by shock wave synthesis, wherein an explosive charge is utilized to shock a mixture of carbon and a metal solvent/catalyst. An example of the shock wave synthesis technique can be found in U.S. Patent No. 3,401,019, which issu on September 10, 1968, in the names of Cowan et al . Drawbacks of the sho wave synthesis procedure are that the diamond which is produced is routinely contaminated with dissolved nitrogen and metal (e.g., iron). I addition, the recovery of diamond particles produced requires elaborate chemical processing to separate the diamond particles from the surroundin materials within the reaction chamber (e.g., graphite and metal). Moreover, this method typically produces only submicron diamond powders. In a third technique, diamond powder can be made by precipitation of diamond within certain amorphous metals which are saturated with carbon. For example, U.S. Patent No. 4,485,080 to Shingu et al., which issued on November 27, 1984, describes a multi-step process for the rapid solidification of carbon-containing alloys followed by the precipitation diamond particles within the amorphous metal at temperatures above 100 ^β C. The diamond is thereafter recovered from the metal by acid digestion. In a more recent development, thin diamond films are synthesized from the vapor phase by an activated chemical vapor deposition (CVD) process. Typically, during such CVD processes, diamond particles nucleate on the surface of an appropriate substrate heterogeneously and thereafter grow in size. The particles thus produced may be widely separated or may be clos

enough to coalesce into a continuous diamond film. Exemplary techniques showing various aspects of the CVD process can be found in the following patents: U.S. Patent No. 4,882,138, which issued on November 21, 1989, i the name of John Pinneo, which discloses the use of the combination of diamond particles, atomic hydrogen and a gaseous carbon source, which, wh processed, results in diamond being epitaxially deposited on the diamond particles; U.S. Patent No. 4,958,590, which issued on September 25, 1990, in the name of Robert Goforth, which discloses a specific microwave assisted CVD process and apparatus; U.S. Patent No. 4,985,227, which issu on January 15, 1991, in the names of Ito et al., which discloses contacti a substrate material with a gaseous source of excited carbon monoxide and excited hydrogen and causing diamond to be deposited onto the substrate; and U.S. Patent No. 5,112,643, which issued on May 12, 1992, in the names of Ikegaya et al . which discloses the use of a raw material gas which includes a carbon source and hydrogen and activating the raw material gas by a thermoelectron—radiating device and by formation of a DC plasma whi results in the deposition of a diamond film on the surface of the substrate. In addition, the CVD process for the formation of diamonds ha been reviewed by R. C. DeVries, Annual Review of Materials Sciences 17:16 (1987); A. R. Badzian and R. C. DeVries, Mat. Res. Bull. 23:385 (1988); a J. C. Angus and C. C. Hayman, Science 241:915 (1988). The art further shows that graphite can be a source material for the formation of various gaseous carbon-based species which are capable of depositing on a large, single crystal of diamond, B. V. Spitsyn, L. L. Bouilov and B. V. Derjaguin, Prog. Crystal Growth and Charact. 17:79 (1988). However no one has to date used the principle of CVD processing to form any objec other than a polycrystalline diamond film.

Another technique for the formation of diamond is disclosed in U.S. Patent No. 4,997,636, which issued on March 5, 1991, in the name of Johan Prins. This patent discloses the use of a non-diamond substrate material having a face-centered cubic crystal structure. The substrate is ion implanted with carbon atoms which are later induced to diffuse out of the substrate and grow epitaxially on a surface of the substrate.

A still further technique for the formation of diamond utilizes a combustion flame. Specifically, U.S. Patent No. 5,075,096, which issued December 24, 1991, in the names of Tanabe et al . discloses burning a combustible gas containing carbon in a combustion-supporting gas which contains oxygen to create a reduction atmosphere, and precisely controll the humidity of the reduction atmosphere, and inserting a substrate into the combustible gas flame to form diamond on a surface of the substrate; and U.S. Patent No. 5,135,730, which issued on August 4, 1992, in the na of Suzuki et al , discloses forming and burning a mixed gas of a hydrocar fuel gas and oxygen to form a flame and contacting the flame with the surface of a substrate to form diamond on said substrate.

All of the above-discussed techniques for the production of diamond suffer from one or more of the following drawbacks: high cost of manufacture, complex production equipment, limited sizes and shapes for diamond production, etc. The present invention overcomes the above described disadvantages inherent in various methods known in the art for the synthesis of diamond and other materials. The invention presents a novel method for the manufacture of various materials including, but not limited to, diamond films, shaped diamond products, boron nitride films, shaped boron nitride products, etc.

Summary of the Invention

The present invention relates to a novel process for the manufacture of various solids including diamond films, shaped diamond products, boro nitride films, shaped boron nitride products, silicon films, shaped sili carbide products, etc. With regard to the synthesis of diamond, the process of the present invention is a significant improvement over known formation techniques such as high temperature/high pressure reactions, solid precipitation reactions, shock wave synthesis, CVD techniques, combustion flame techniques, etc. The present invention utilizes a novel combination of starting materials and processing conditions to result in novel materials (e.g., diamond). Specifically, with regard to diamond formation, the combination of one or more starting source(s) of carbon i non-vapor form (e.g., certain solids and liquids including, but not limi

to, amorphous carbon, carbon black, carbon powder, carbon fibers, graphi charcoal, polymer materials containing carbon, glassy carbon non-vapor carbon precursor materials, etc.) with one or more appropriate seed material (s) present in addition to the starting source of carbon or inherently present in the starting source of carbon, said seed material ( having a diamond or diamond-like crystalline structure (e.g., diamond crystals, silicon, silicon carbide, cBN, various face-centered cubic structures which are similar to the crystal lattice of diamond, or other isostructual materials, etc.) and/or one or more seed material precursor which, under the process conditions of the invention, may form one or mo seed materials in situ (e.g., Ni, Cu, Mo, Zr, Pt, Pd, etc.) may, when heated to a suitable temperature (e.g., 300 ^β C-2000 ^β C, and more preferabl 300 ^β C-1600 ^β C and even more preferably 700 ^β C-1000 ^β C) in the presence of a suitable atmosphere, either externally supplied or internally created (e.g., hydrogen and other atmospheres such as argon, nitrogen carbon, oxygen and mixtures thereof which do not need to exceed about one (1) atmosphere of pressure, or even pressures greater than one atmosphere), form diamond materials as coatings or as free-standing (i.e., self- supporting) bodies of various desirable sizes and shapes. Suitable starting material mixtures for use in connection with the present invention may be formed by many conventional techniques includin simply mixing solid materials together in a homogeneous or non-homogeneo manner. Such mixing may include many traditional mixing processes such dry mixing processes (e.g., ball milling) traditional wet mixing process etc. A particularly preferred method for mixing solids together is know as the nanocomposite formation technique. The description of nanocompos formation techniques are well known in the literature as set forth in th following references, the subject matter of which are herein expressly incorporated by reference: Rustum Roy, Sol-Gel Processes: Origins, Problems, Products, Am. Ceram. Soc. Bull. 60:383 (1981); Rustum Roy, New Hybrid Materials made by Sol-Gel Technique, Bull. Am. Ceram. Soc. 61:374 (1982); Rustum Roy, Ceramics from Solutions: Retrospect and Prospect, M Res. Soc. Annual Mtg. Abstracts, p. 370 (1982); Rustum Roy, New Metal- Ceramic Hybrid Xerogels, Mat. Res. Soc. Annual Mtg. Abstracts, p. 377

(1982); Rustum Roy, Ceramics by the Solution-Sol-Gel Route, Science 238:1664-1669 (1987); Rustum Roy, S. Komarneni and W. Yarbrough, Some Ne Advances with SSG-Derived Nanocomposites, Chapter 42, Ultrastructure Processing of Advanced Ceramics, John MacKenzie and Don Ulrich (eds.), Wiley Interscience, pp. 571-588 (1988). However, in many instances, ver desirable products can be formed without the need for the homogeneous mixing offered by the nanocomposite formation technique.

Many different apparatuses may be suitable for use in connection wit processing the starting materials of the present invention. Some primar considerations in choosing acceptable processing apparatuses may include, for example, the ability of the apparatus to contain a controlled atmosphere and the ability to heat, at least locally, the starting materials to a sufficiently high temperature so as to permit reactions according to the present invention to occur. Accordingly, acceptable processing apparatuses include, for example, chemical vapor deposition apparatuses which are assisted by such means as, for example, microwave generator apparatuses, radio frequency generator apparatuses, filament heating apparatuses, direct heating apparatuses, etc. In addition, with regard to diamond formation, the present invention may also function acceptably in the presence of hydrogen or acetylene flames either contai within a controlled atmosphere area or not contained in a controlled atmosphere vessel .

It should be understood that this disclosure focuses primarily on th production of diamond coatings and various diamond shapes. However, despite such focus, it should be clear to an artisan of ordinary skill th the concepts of the invention translate directly in numerous parallel material systems (e.g., boron nitride), each of which material systems should be benefitted by this invention in a similar manner.

Objects of the Invention

An object of the invention is to develop a new process for the manufacture of various compositions of films (e.g., diamond) using starti materials in a non-vapor form (e.g., a non-vapor source of carbon for diamond film formation).

It is a further object of the invention to develop a process for the manufacture of various self-supporting bodies (e.g., diamond) to net or near-net shape using starting materials in a non-vapor form (e.g., a non- vapor source of carbon for self-supporting diamond structures). It is also an object of the invention to develop a process for the synthesis of various materials (e.g., diamond), which process can be conducted in various reactors including CVD reactors assisted by microwav radiowave, etc., hot-filament reactors and in the case of diamond, in the presence of a hydrogen or an acetylene flame, either contained or not contained within a closed environment.

It is also an object the invention to manufacture cubic boron nitrid from an appropriate non-vapor starting material.

Description of the Drawings FIG. 1 is an SEM photomicrograph taken at about 13000X of a typical carbon-source material used in comparative Example 2;

FIG. 2 is a Raman Spectrum of a material formed in accordance with t present invention as set forth in Example 1;

FIG. 3 is an SEM photomicrograph taken at about 2150X of the material of the present invention formed in accordance with Example 1;

FIG. 4 is a Raman Spectrum of a comparative example material formed i accordance with Example 2;

FIG. 5 is an SEM photomicrograph taken at about 2270X of the comparative example material formed in accordance with Example 2; FIG. 6 is an SEM photomicrograph taken at about 2220X of the material formed in accordance with Example 8;

FIG. 7 is a schematic view of the alumina tube furnace which was utilized in Examples 15-17;

FIG. 8 is a Raman Spectrum of a material formed in accordance with Example 8;

FIG. 9 is a schematic view of the microwave plasma assisted chemical vapor deposition reactor which was utilized in Examples 1, 2, 3 and 6;

FIG. 10 is a Raman Spectrum of a material formed on a silicon substrate in accordance with the present invention as set forth in Exampl 6;

FIG. 11 is a Raman Spectrum of a material formed on a molybdenum substrate in accordance with the present invention as set forth in Exampl 6;

FIG. 12 is an SEM photomicrograph taken at about 4500X of the materi formed on the silicon substrate in accordance with Example 6;

FIG. 13 is an SEM photomicrograph taken at about 4500X of the materi formed on the molybdenum substrate in accordance with Example 6;

FIG. 14 is an x-ray powder diffraction pattern of the material forme in accordance with Example 7;

FIG. 15 is an x-ray diffraction pattern taken of the colloidal graphite/diamond seed/pol vinyl alcohol binder spherical balls of Example before the hydrogen/oxygen flame treatment; and

FIGS. 16a and 16b are SEM photomicrographs of the material formed in accordance with Example 7;

FIG. 17 is an SEM photomicrograph taken at about 2400X of the materi formed in accordance with Example 10; FIG. 18 is a Raman spectrum of the material formed in accordance wit Example 11;

FIG. 19 is an SEM photomicrograph taken at about 353X of the material formed in accordance with Example 11;

FIG. 20 is a Raman spectrum of the material formed in accordance wit Example 12;

FIG. 21 is an SEM photomicrograph taken at about 347X of the material formed in accordance with Example 12;

FIG. 22 is an SEM photomicrograph taken at about 490X of the material formed in accordance with Example 12; FIG. 23 is an SEM photomicrograph taken at about 620X of the material formed in accordance with Example 3, Sample A;

FIG. 24 is an x-ray powder diffraction pattern of the material formed in accordance with Example 3, Sample A;

FIG. 25 is a Raman Spectrum of the material formed in accordance wi Example 3, Sample A;

FIG. 26 is a representative SEM photomicrograph taken at about 750X a material formed in accordance with Example 4, Sample E; FIG. 27 is a representative SEM photomicrograph taken at about 1500 of a material formed in accordance with Example 4, Sample E;

FIG. 28 is a representative SEM photomicrograph taken at about 500X a material formed in accordance with Example 4, Sample E;

FIG. 29 is a schematic view of the Astex microwave plasma assisted chemical vapor deposition reactor which was utilized in Example 9;

FIG. 30 is an SEM photomicrograph taken at about 604X of the materi formed in accordance with Example 9;

FIG. 31 is a Raman Spectrum of the material formed in accordance wit Example 9; FIG. 32 is a schematic view of the hot filament type diamond deposition/conversion system which was utilized in Example 14;

FIG. 33 is an x-ray powder diffraction pattern of the material forme in accordance with Example 15;

FIG. 34 is an x-ray powder diffraction pattern of the starting materials utilized in accordance with Example 15;

FIG. 35 is an x-ray powder diffraction pattern of the material forme in accordance with Example 16;

FIG. 36 is an x-ray powder diffraction pattern of the starting materials used in accordance with Example 16.

Detailed Description

Detailed embodiments of the present invention are herein disclosed. However, it should be understood that the disclosed preferred embodiment are merely illustrative of the invention which may be embodied in many forms. Accordingly, specific details disclosed herein are not to be interpreted as limiting, but merely as support for the invention, as claimed, and as representative examples for teaching one skilled in the to employ the present invention in an appropriately detailed fashion.

The present invention relates generally to a novel process for the formation of coatings or films on appropriate substrate materials. The present invention further relates generally to a novel process for the formation of shaped self-supporting materials. Common to each of the preferred embodiments of the invention is the utilization of certain non- vapor starting materials which are processed in a novel manner.

When the present invention is utilized to form a desirable coating o an appropriate substrate material a first step in the process of the present invention is to form an appropriate mixture of materials which is to be coated onto the substrate material. Some important considerations which may be taken into account in forming such mixtures include: (1) t homogeneity of the mixture; (2) the particulate size of the materials in the mixture (e.g., in some embodiments very fine particulate less than a micron in size are desirable, whereas in other embodiments, much larger particulate is desirable); (3) reactivities of the materials in the mixtu with each other or other materials exposed to the mixture during processi of the mixture; and (4) the need, in certain cases, for a binder to assis in holding the mixture together during processing thereof. Each of these considerations is discussed in greater detail below. Likewise, when the present invention is utilized to form a self- supporting (e.g., free-standing) shaped material, each of the above- discussed considerations may also be important. However, depending upon the particular thickness and complexity of shape of a body to be formed, some additional considerations may be necessary to be taken into account. Such additional considerations may include: (1) the ability to shape the starting material utilized in the invention into a suitable configuration (2) the ability for the starting material to maintain its shape during processing thereof so as to permit the formation of net or near-net shape materials (i.e., the size and shape of the resulting body corresponds substantially to the size and shape of the starting material); and (3) th ability, if desired, for the starting material to maintain at least some porosity for at least a portion of the processing thereof, to permit a vapor phase species, when used, to interact with, for example, at least a

portion of the non-vapor phase shaped starting material, each of which additional considerations are discussed in greater detail below.

The starting materials which comprise either the coating or the self supporting body typically include at least two materials or alternatively comprises a single material which performs a dual role. The first material, which typically is present in a greater amount, functions as a source material and the second material, which typically is present in a lesser amount, functions as a seed material. The source material may contain one or more additional materials which favorably influence physical, mechanical, electrical, etc., properties of the final body. Th phrase "source material" in this context should be understood as meaning one or more material (s) which is/are capable, under the process condition of the invention, of interacting with one or more seed material (s) and/or one or more seed material precursor(s), to grow one or more species from one or more surfaces of the seed material (s) or to grow one or more speci from one or more interfaces between the source material and seed material and/or seed material precursor. The phrase "source material precursor" i this context should be understood as meaning one or more materials which, under the process conditions of the invention, may form one or more sourc materials in situ. Further, it is possible that certain materials may function as (1) source materials and/or source material precursors and (2 be a supplier of an additional material which benefits the processing and/or the properties of the final body (e.g., certain materials like, fo example, glassy carbon, may provide both a source material, such as carbo and a desirable localized atmosphere, such as hydrogen). The phrase "see material" in this context should be understood as meaning one or more material (s) which is/are capable, under the process conditions of the invention, of providing one or more crystalline structures onto which or from which the source material (s) is/are capable of being deposited or growing one or more desirable species therefrom. The phrase "seed materi precursor" in this context should be understood as meaning one or more materials which, under the process conditions of the invention, may form one or more seed materials in situ. In addition, it should be understood that certain materials may function both as seed materials and seed

material precursors under certain processing conditions. Further, it is possible that certain materials may function as (1) seed materials and/or seed material precursors and (2) a supplier of an additional material whi benefits processing and/or properties of the final body. Additionally, i is possible that certain materials may function as (1) seed materials and/or seed material precursors and (2) a supplier of a material which forms at least a localized atmosphere which benefits processing and/or properties of the final body (e.g., certain metal hydrides may donate bot (1) seed materials and/or seed material precursors and (2) hydrogen). It should be further understood that one or more source material (s) and/or o or more source material precursors and/or one or more seed material (s) and/or seed material precursor(s) may be used in combination with each other to influence favorably the processing of the final body and/or resultant properties of the final body. The mixture of source material (s) and seed material (s) and/or precursors thereof may be homogeneous or non-homogeneous, depending on a number of different factors. For example, in some embodiments of the invention, an intimate or substantially homogeneous mixture may be desirable. A homogeneous starting material mixture may result in lower processing temperatures and/or shorter processing times and/or more homogeneous final bodies. Accordingly, the nanocomposite formation technique for making mixtures, as discussed above herein, may be ideally suited for numerous applications of the invention. However, it has also been shown that much less sophisticated methods of mixing are also acceptable. Additionally, non-homogeneous mixtures may be desirable for certain applications where, for example, graded final bodies are desirabl and/or certain processing modifications are required. In this regard, no homogeneous mixtures could be utilized to grade the composition of a body and/or the microstructure of a body. Examples of applications where a no homogeneous mixture could be useful include filtration applications, catalysis applications, biomaterials, etc.

The relative particle size of the source material (or precursors thereof) compared to the seed material (or precursors thereof) may range from being approximately the same average particle size to either of the

source material (or precursors thereof) or the seed material (or precurso thereof) having an average particle size which is tens to thousands of times larger than the average particle size of the other material. In general, the source material should be capable of interacting with the se material in a manner which efficiently and economically results in the production of desirable materials. Accordingly, it should be apparent to an artisan of ordinary skill that a limitless combination of source materials (and/or precursors thereof) and seed materials (and/or precurso thereof) is possible depending on the desired processing characteristics the materials and the desired properties of the final body to be produced The ability of the starting material mixture to hold its shape, whether the starting material mixture is applied as a coating on a substrate or forms a self-supporting body, may be important for certain applications. For example, the ability to form net or near-net shapes fr a starting material mixture may be critically important. In such instances, a binder may be necessary to cause the starting material mixtu to be capable of being shaped and holding its shape during at least part the processing thereof. It is possible that both organic and inorganic binders may be suitable for use with the present invention. However, typically, when an organic binder is utilized, the amount of binder included in the starting material mixture should be minimized, so as to ameliorate any undesirable aspects which may result due to the presence o the binder (e.g., binder removal, etc.).

Techniques utilized to place starting materials for coatings on substrate materials and techniques utilized to form self-supporting starting material compositions include many traditional forming technique such as spraying, dry pressing, extrusion, tape casting, soaking or immersion, hot and cold isostatic pressing, vacuum impregnation, etc. Fo example, it may be desirable for a starting material mixture to be applie onto or into a porous body such as a woven cloth or fibers or any other porous body where it could be considered to be desirable to form a coatin (e.g., a diamond coating) on at least a portion of a wall which defines a least some of the porosity of the porous body. Thus, for example, a diamond coating could be placed onto at least a portion of any porous

material where such diamond coating could provide enhanced performance (e.g., filtration devices, extrusion dies, bio edical materials, etc.).

It is also possible to form a sol-gel of appropriate starting materials. In such case, fibers could be drawn or pulled from the sol-g mixture and thereafter processed according to the present invention.

Further, carbon fibers, which may function as a source material, could b suitably coated with, for example, a seed material and processed accordingly to the present invention. Accordingly, the production of diamond fibers could be achieved by practicing certain techniques of the present invention. Moreover, appropriate starting materials could be impregnated with a polymer (e.g., a thermosetting polymer) which could thereafter be shaped by any conventional technique and then processed according to the present invention to form a desirable product. Additionally, a polymer could itself be shaped into a desired shape and then processed according to the present invention. When it is desired to utilize a polymer in combination with some other appropriate starting materials, the ratio of starting material mixture to polymer can be controlled to assure both the formability of the polymer/starting materia mixture as well as the properties of the final product. Once an appropriate starting material mixture has been formed, which includes at least one source material (or precursors thereof) and at leas one seed material (or precursors thereof), the mixture is processed in accordance with the invention. Specifically, typically, the starting material mixture is heated to a suitable temperature in a suitable environment to permit formation or growth of one or more desirable specie onto or from one or more seed materials. Numerous apparatuses are suitab for use in connection with the practice of the present invention. For example, those apparatuses which are capable of maintaining a controlled atmosphere (e.g., an atmosphere which does not adversely affect the formation of desirable bodies or an atmosphere which favorably influences the formation of desirable bodies) and which can achieve temperatures whi permit the source material to deposit on and/or grow from, the seed material, are acceptable. Such apparatuses include, but are not limited to, chemical vapor deposition apparatuses which may or may not be assiste

by microwave generator apparatuses, radio frequency generator apparatuses filament heating apparatuses, etc. Common to each of these apparatuses i the capability to heat a material within at least a portion of the apparatus to a relatively high temperature (e.g., 300 ^β C-2000 ^β C, more preferably 300 ^β C-1600 ^β C and even more preferably 700 ^β C-1000 ^β C) while maintaining a controlled atmosphere. In the present invention, the contr of temperature and time are important for controlling the particle size and/or morphology of any crystalline species that are produced. In general, larger crystals can be achieved with higher temperatures and/or longer times, while relatively smaller crystals can be achieved with lowe temperatures and/or shorter times. Moreover, by supplying certain favorable atmospheres (e.g., in the case of diamond formation atmospheres of, for example, hydrogen, nitrogen, carbon, oxygen, argon, etc., and mixtures thereof) to an appropriate starting material mixture, such atmosphere(s) may also influence favorably the particle size and/or morphology of any crystalline species that are produced. In general, the presence of a favorable atmosphere may increase particle size and/or resu in a more dense structure in the final body. In addition, the atmosphere may be static or dynamic (i.e., flowing). In certain cases a dynamic atmosphere my favorably influence the properties of a final body which is formed according to the present invention. It should be understood by an artisan of ordinary skill that the precise combination of processing conditions for practicing the invention are dependent on the desired characteristics of the resulting bodies. In certain aspects of the invention the apparatuses discussed above may be used to assist in the formation of a plasma which also may interac favorably with the starting material mixture. The formation of a plasma adjacent to at least a portion of the starting material mixture may facilitate or influence the formation of desirable materials or bodies fr the starting material mixture. Without intending to be bound by any particular theory or explanation, it is possible that formation of a particular plasma, which is induced to contact at least a portion of a starting material mixture, may favorably impact or facilitate the movemen of the source material to contact the seed material. For example, one or

more species in a formed plasma may assist in transporting one or more species of a source material to at least a portion of a seed material. I such transport occurs, deposition or growth of a desirable material from on the seed material may occur. A plasma can be formed by conventional techniques which include inputting a vapor-phase material or combination of materials into a controlled atmosphere apparatus and exciting such material (s) by, for example, microwave, radiowaves, resistance heating, etc., to form one or more gaseous species. Additionally, a plasma can be formed by exciting o or more source materials (or source material precursors) or by adding one or more precursor plasma materials to a source material such that when th precursor plasma material is excited by any of the means discussed above, desirable plasma may form and be in contact with at least a portion of th starting material mixture. In some instances the formation of a plasma m be essential in order to achieve a desirable amount of deposition or grow on or from the seed material (s), whereas in other cases a plasma may not required or may not perform an essential role in such deposition or growt

To assist in understanding some important aspects of the invention, a comparison of the invention, when applied to diamond formation, against traditional chemical vapor deposition processes utilized for diamond formation may be useful.

In a traditional CVD process for diamond formation, the carbon source always a gas (e.g., methane), is mixed with 95-99 percent hydrogen and th hydrogen is excited, for example, thermally or by a microwave field. In general, excitation of the carbon source gas results in the production of complex mixture of various hydrocarbon species, plus some atomic hydrogen and molecular hydrogen. The produced carbon atoms can then agglomerate a very small nuclei on selected substrate materials. These agglomerated nuclei contain both sp ^z (i.e., graphitic structure) and sp ³ (i.e., diamon structure) bonding. Once at least some of the aforementioned nuclei have been deposited, atomic hydrogen, which is produced from the excitation of H2, tends to dissolve or react away all of the sp ² nuclei leaving predominantly sp ³ nuclei which form the diamond structure. The diamond

nuclei may then grow into separate diamond crystals and eventually form a continuous film.

In contrast, with regard to traditional CVD diamond formation, the present invention does not rely on the use of a carbon-supplying starting vapor to produce diamond coatings and self-supporting diamond bodies.

Rather, the present invention utilizes a non-vapor (e.g., solid or liquid carbonaceous starting material. Specifically, in one preferred embodimen of the invention, a diamond seed material is provided (e.g., mixed with o inherently present as a portion of a carbon source material) along with a non-vapor phase carbon source material. The seed material and source material may be homogeneously or non-ho ogeneously mixed together. A supply of hydrogen (e.g., hydrogen gas or, atomic hydrogen either externally supplied or created in situ from one or more materials in the seed material (or seed material precursors) or the source material (or source material precursors) may be supplied to the mixture of carbon sour material and diamond seed material. The mixture and supply of hydrogen a exposed to a high temperature (e.g., 300 ^β C-1600'C) which permits a majori of sp ² graphitic carbon to be converted to the sp ³ diamond structure. Additionally, carbon from the carbonaceous starting material is permitted to interact with the sp ³ diamond seeds and results in the growth of diamo from or on the seed crystals.

An artisan of ordinary skill should understand that a majority of th carbon which forms the final desired diamond product, is supplied by the carbon source material adjacent the diamond seeds. By supplying carbon i this manner, diamond films and self-supporting diamond bodies previously believed to be difficult, if not impossible to achieve, can be readily formed. In addition, the process of the invention can be particularly attractive when a carbon source material is placed in the immediate vicinity (e.g., from several nanometers to several microns) of the diamon seed crystals. While not wishing to be bound by any particular theory or explanation, it appears possible that the carbon source material may transform to diamond by a vapor phase, or catalytic molten intermediary o even a solid state transformation process, which is made possible, in par by the presence of the very fine diamond seed crystals which provide for

epitaxial nuclei for the growth of the larger diamond crystals. Moreover it is also plausible that the juxtaposition and concentration of the carb source material relative to the diamond seed crystal enhances the interaction between the materials by, for example, increasing the amount possible reactions between the carbon source and the diamond seeds.

In a fourth aspect of the present invention regarding the formation diamond, additional gases utilized in traditional CVD processes may, optionally, be added. For example, hydrocarbon gasses such as methane ma be inputted to the source material/seed material mixture to cause even further growth of diamond crystals onto or even between those crystals produced by, for example, the above-discussed reactions. Accordingly, th amount of hydrocarbon gas provided can be controlled in a manner which permits even further control of the microstructure of a formed body.

With respect to diamond formation according to the present invention, non-vapor phase carbon source materials appear to include virtually any form of carbon. However, those forms which are particularly preferred include finely dispersed carbon (1 < μm) , commercially available AQUA-DA colloidal graphite, carbon black, glassy carbon, soot, lamp black, organi polymers which are capable of being converted to carbon in situ, etc. Certain carbon source materials may contain one or more additional materials which favorably influence(s) the resultant diamond product. Fo example, if a carbon source material was doped with nitrogen and/or phosphorus (e.g., C-N and/or C-P bonds were formed in the carbon source material) desirable doping of the resultant diamond product could be expected to occur (e.g., such products could be used for electronic applications such as P/N junctions). Moreover, it is possible to form large single crystal diamonds by, for example, coating multiple layers of ve y fine mixtures comprising carbon onto a surface of a seed and causing said multiple layers to sequentially or substantially simultaneously convert to diamond.

Acceptable diamond seed materials include diamond powder but any seed of diamond or diamond-like structures (e.g., cBN, silicon, silicon carbid various face-centered cubic crystalline structures which are similar to t crystal lattice of diamond, or other isostructual materials, etc.), could

also function as appropriate seed materials. In addition, certain materials may also function as seed material precursor(s). Such material may be used alone or in addition to seed materials and/or other seed material precursor material (s). It is possible that under certain processing conditions a seed material precursor may also function as a s material. Certain important considerations in selecting seed material (s) and/or seed material precursor(s) include the chemistry of the material (s (e.g., the ability of the material (s) to catalyze the formation of diamo the stability of the material(s) (e.g., to withstand certain aspects of processing conditions of the invention), the structure and lattice const of the material (s) (e.g., to approximate those of diamond), etc. Acceptable seed materials and/or seed material precursors in addition to those discussed above include, for example, Ni, Si, Cu, Fe, Mo, Pt, Pd, etc. Moreover, certain materials may perform multiple roles during the process of the present invention. Specifically certain materials may function as (1) a seed material and/or seed material precursor and (2) a source of hydrogen. In this regard, simple or complex metal hydrides (e.g., lanthanum hydrides, tantalum hydrides, lanthanum-nickel hydrides, zirconium hydrides, titanium hydrides, etc.) may supply hydrogen, which i useful in the production of diamond, in addition to seed materials and/or seed material precursors (e.g., one or more of lanthanum or nickel or compounds thereof).

The selection of any particular metal hydride is dependent upon a number of factors including the processing temperature at which the metal hydride disassociates into its component parts. In a preferred embodimen of the invention, the metal hydride disassociates at a temperature which at or near the processing temperature of the invention. In this instance hydrogen from the disassociated metal hydride is available to interact favorably with the carbon source material. If the metal hydride disassociated at too high or too low of a temperature, the hydrogen may n be able to influence favorably the processing and/or properties of the final body.

Further, in certain aspects of the invention, it may be determined that an atmosphere of hydrogen, whether local or global (i.e., throughout

the contents of a reaction vessel) may be desirable. In certain cases, a metal hydride material may be capable of supplying a sufficient amount of hydrogen (e.g., at least a local atmosphere) to achieve desirable reactions. However, in other cases, the metal hydride material may suppl hydrogen in addition to an external supply source of hydrogen.

In another preferred embodiment, boron nitride (e.g., cubic boron nitride) can be made in a manner similar to the methods of the present invention discussed above and which were utilized to form diamond.

With respect to the growth of cubic BN from solid state sources, the prediction that a BN usually prepared in the graphitic structure could be made into the diamond structure should be clear to anyone familiar with th science of crystal chemistry. Van Arkel was the first to explicitly refe to this in 1926. In addition, a research team at General Electric successfully converted hexagonal BN to cubic BN in 1955 at elevated pressures (>50kb) and temperatures (>1000T). However, as discussed above such traditional technique suffers from many disadvantages.

The following examples are offered to illustrate particular embodiments of the invention, but are not intended to limit the invention claimed in the appended claims.

Example 1

This Example demonstrates a first method for forming diamond according to the present invention by utilizing a microwave plasma assiste CVD reactor. A starting source of carbon, as discussed in the detailed description, was prepared by placing a sample of AQUA-DAG ^® E colloidal graphite (Acheson Product Code No. 5300021, purchased from Ted Pella, Inc. Tustin, CA) into a small glass beaker. The AQUA-DAG ^® E was diluted with a amount of deionized water having a resistivity of greater than about 7 M ohms, so that the ratio of AQUA-DAG® E to water was about 1:3. The AQUA- DAG ^® E/deionized water mixture was stirred by hand for about 10 minutes utilizing a stainless steel spatula which had previously been thoroughly degreased with acetone in an ultrasonic bath, washed in deionized water in an ultrasonic bath, and dried.

The seed material, as discussed in the detailed description, was prepared by first cleaning a 3 ml glass bottle by degreasing the bottle with acetone in an ultrasonic bath and then washing the bottle with deionized water in the ultrasonic bath. This procedure was repeated several times and, finally, the bottle was hot air dried (utilizing a commercially available hair dryer) after a final methanol rinse.

The cleaned 3 ml glass bottle was placed onto a microbalance and a sample of diamond powder (supplied by South Bay Technology) weighing abou 0.075 grams and having an average particle size of about 3-6 microns was placed into the glass bottle. About 0.525 grams of deionized water was then placed into the glass bottle and mixed with the diamond powder by utilizing a fine, cleaned wire and hand-stirring the diamond powder and water together.

A silicon substrate measuring about 1 cm x 1 cm and having a thickness of about 0.2 mm was cut from a larger silicon wafer utilizing a diamond scriber. The silicon substrate was cleaned in the following manner. About 25 ml of high purity acetone was placed into a clean 50 ml Pyrex ^® glass beaker. Utilizing a clean, fine tweezer, the silicon substrate was placed into the beaker and submerged in the acetone. The beaker, containing the acetone and the silicon substrate, was placed into the fluid containing vessel of an ultrasonic cleaner. The fluid in the ultrasonic cleaner was water and care was taken to assure that the water level in the fluid containing vessel was maintained below the top of the beaker. The silicon substrate was then subjected to four acetone ultrasonic baths, changing the acetone after each bath. Each ultrasonic bath lasted about 3 minutes. After four acetone ultrasonic baths, the beaker was removed from the ultrasonic cleaner and the acetone was remove from the beaker. Then, about 25 ml of deionized water having a resistivi greater than about 7 megaohms was placed into the beaker and the silicon substrate was subjected to four separate ultrasonic baths utilizing deionized water as the bath, with the deionized water being changed after each ultrasonic bath. Each ultrasonic bath lasted about 3 minutes. Afte the fourth deionized water ultrasonic bath, the beaker was removed from t ultrasonic cleaner and the deionized water was removed from the beaker.

About 2 ml of high purity methyl alcohol was then poured into the beaker and the silicon substrate was subjected to the ultrasonic bath for about minute. After about 1 minute, the beaker was removed from the ultrasonic cleaner and the methyl alcohol was removed from the beaker. The silicon substrate was then removed from the beaker and dried with a warm air blow (i.e., a commercially available hair-dryer set on "low").

The silicon substrate, now cleaned and dried, was placed into a sma petri dish and utilizing a microbalance, a silicon substrate weight of about 0.0735 grams was recorded. The AQUA-DAG® E/deionized water mixture was thoroughly remixed and utilizing a fine, cleaned spatula, a droplet (weighing about 0.0017 grams of the AQUA-DAG ^® E/deionized water mixture was applied to about the cente of one of the 1 cm x 1 cm sides of the silicon substrate.

The diamond powder/deionized water mixture was thoroughly remixed a utilizing a cleaned 1 mm diameter wire, a very small droplet (weighing about 0.0118 grams) of the diamond powder/deionized water mixture was als placed approximately in the center of the same 1 cm x 1 cm side of the silicon substrate so that both of the mixtures could be mixed together. facilitate proper mixing and even spreading of the AQUA-DAG ^® E/deionized water mixture and the diamond powder/deionized water mixture together, on drop of deionized water was also applied approximately to the center of t same 1 cm x 1 cm side of the silicon substrate. Then, by utilizing the rounded tip of the spatula, the AQUA-DAG® E/deionized water mixture, the diamond powder/deionized water mixture and the deionized water drop were thoroughly mixed by hand for about 4 minutes and then slowly and evenly spread onto the surface of the silicon substrate, such that substantially all of the 1 cm x 1 cm surface of the silicon substrate was substantially evenly coated with the mixture.

The petri dish holding the coated silicon substrate was then placed onto a horizontal surface in a room temperature, air atmosphere, dust-fre cabinet and left to dry for about 3 hours. After about 3 hours, a temperature of about 80 ^β C was established within an air atmosphere, ambie pressure oven and the petri dish containing the coated silicon substrate was removed from the dust-free cabinet and placed into the oven. After

about 5 minutes, the petri dish and the coated silicon substrate were removed from the 80 ^β C oven and placed into an air atmosphere, ambient pressure oven having a temperature of about 150*C. After about 5 minutes, the petri dish and the coated silicon substrate were removed from the ove and the coated silicon substrate was placed onto a microbalance and a weight of about 0.0784 grams was recorded.

Figure 9 is a schematic view of a microwave plasma assisted chemical vapor deposition reactor (MPCVD) which was utilized in this Example. Tabl I provides in tabular form a list of the different components of the MPCV shown in Figure 9, wherein the reference numerals utilized in Figure 9 are cross referenced to the different components of the MPCVD system.

Table I Reference Numerals Component Parts 1 quartz window

2 optical pyrometer

3 gas inlet tube

4 quartz tube

5 piasma 6 microwave cavity

7 tuning short

8 substrate holder

9 nitrogen cylinder

10 exhaust valve 11 vacuum pump

12 substrate adjust

13 electronic control circuits

14 mass flow controllers

15 gas cylinders 16 pressure transducer

17 iris

18 microwave stub-tuner

19 F/R power meter

20 dummy load 21 microwave power-generator

22 circulator

23 directional coupler

24 exhaust system

25 gas flow inlet control system 26 metallic multi-port adapters

27 beyond cut-off tubes

28 high-vacuum stoppers

As shown in Figure 9, the MPCVD system consists of a quartz tube 4 passing through the maximum field intensity region of a microwave cavity The tube 4 is provided with vacuum type metallic multi-port adapters 26 a both ends. The ports are connected to a gas flow (inlet) control system consisting of gas cylinders 15, mass flow controllers 14, electronic control circuits 13, high-vacuum stoppers 28, and gas inlet tube 3, on th upper end and an exhaust system 24 consisting of an exhaust valve 10, a nitrogen cylinder 9, and a vacuum pump 11, at the lower end. A quartz window 1 is provided at the top of the quartz tube 4 for viewing as well measuring the substrate temperature with an optical pyrometer 2. Water cooling jackets (not shown) are provided around the quartz tube 4 and the resident microwave cavity 6. The silicon substrate is positioned on the

graphite substrate holder 8 (having a diameter of about 18 mm and having a projecting rim of about 0.5 mm, machined from a quantity of high-grade graphite), supported by a quartz/stainless steel rod, and is inserted into the reactor from the vacuum type port at the bottom of the quartz tube 4. Use of special 0-rings at the joints (inside the metallic multi-port adapters 26) make it possible to position the substrate and rotate it, by utilizing the substrate adjust 12, if required for centering inside the cavity 6.

A suitable microwave-stub-tuner 18 and wave guide variable tuning short 7 are provided for matching the impedance of the cavity 6 to the microwave power source and for tuning the cavity 6 to the microwave power source frequency, respectively. The use of beyond cut-off tubes 27 on bot sides of the cavity 6 avoid leakage of microwave power from the reactor. Mass flow controllers 14 (M S Instruments, Inc., Andover, MA), along with the electronic control circuits 13, are used to adjust the flow of th gas through the gas inlet tube 3 and through the reactor. The pressure inside the reactor is substantially maintained at a predetermined set valu by an electromechanically operated exhaust valve 10 fitted between the reactor and the exhaust pump 11. The coated silicon substrate was placed into the substrate holder 8 with the coated side facing up. A gas flow rate of about 90 seem of ultrahigh purity hydrogen and about 10 seem of a mixture of 10% methane, balance utrahigh purity hydrogen (i.e., a total gas flow rate of about 100 seem) was established through the gas inlet tube 3 and through the reactor A reactor pressure of about 90 torr was established. The microwave power from the microwave power generator 21 was turned on, thus producing a plasma 5 and the temperature of the coated silicon substrate was raised from about room temperature to about 990 ^* C in about 20 minutes. The gas flow rate, reactor pressure and temperature were maintained for about 6 hours. After about 6 hours, the microwave power was gradually reduced in about 10 minutes and then turned off; the substrate temperature was allowe to cool to about room temperature; the pressure within the reactor was increased to ambient; and the gas flow rate was interrupted completely. The substrate was then removed from the substrate holder 8 and the coated

side of the substrate was analyzed utilizing a microfocus Raman Spectrograph (Model ISA RAM U-1000). The control settings of the Raman Spectrograph were set as follows: laser wave length - 514.532 nm; laser power - 150 mw; slits - 200 urn; increment - 1.00 cm ^" ; magnification = 40 and NB scans = 1.

The coated side of the substrate was subjected to Raman spectroscop and, as shown in Figure 2, a very sharp Raman line around 1332 cm ^"1 was obtained from the coating on the sample. This value corresponds to diamo crystals only. The spectrum also showed that graphitic carbon was practically absent from the scan.

Also, scanning electron microscopy pictures were taken from the coated surface of the silicon substrate and, as shown in Figure 3, showed the polycrystalline morphology of the diamond coating, its pure crystalli structure and good nucleation density. An environmental type SEM (Electroscan ES-30) and a high vacuum type SEM (ISI DS 130) were used for this purpose.

Finally, the coating was analyzed using x-ray diffraction and an x- ray diffraction spectrum showed a peak at d = 2.056 Angstrom, which corresponds to diamond crystals, thus, further confirming the quality of the diamond layer formed on the substrate.

Example 2

The procedures of Example 1 were repeated exactly except that no external isostructural seed material, (i.e. fine diamond powder) was put the coating. In the comparative example the starting material mixture of AQUA-DAG ^® E colloidal graphite, shown in Figure 1, did not show any chang under the process conditions. In this regard, there was no diamond formation in the Raman spectrum as shown in Figure 4, or evidenced by the SEM photomicrograph, as shown in Figure 5.

Example 3

The following samples demonstrate further processing modifications the method of forming diamond set forth in Example 1.

Sampl e A

Aqua-Dag ^® E colloidal graphite, a product of Acheson Colloids Company, Port Huron, MI, Product Code 5300021, was used as the starting source of carbon. About five grams of the Aqua-Dag ^® E was placed into a ml Pyrex ^® glass beaker which had been cleaned along with a stainless ste spatula using several flushes of acetone, deionized water, a final rinse methanol, and drying. Ultrasonic agitation for about 5 minutes was used each stage of the cleaning process in an ultrasonic bath (manufactured b Geoscience Instruments Corporation, New York). While stirring the Aqua-Dag E® with the stainless steel spatula, about 15 ml of deionized water, of resistivity better than 7 M ohms, was added to the Pyrex ^® beaker. A watch glass, cleaned and dried in essentially the same manner as the Pyrex® beaker mentioned above, was us to weigh about 0.250 gram of diamond seed powder, about 2 micron size, (supplied by Warren Diamond Powder Company, Inc.). This diamond powder mixed with the Aqua-Dag E ^® sol and ultrasonicated for about 15 minutes t make a homogeneous diphasic sol of Aqua-Dag E ^® and diamond seeds.

A silicon substrate measuring about 1 cm x 1 cm and having a thickness of about 0.2 mm was cut from a larger silicon wafer using a diamond scriber. The substrate was thoroughly cleaned and dried in essentially the same manner as described in Example 1 and thereafter pla in a clean petri dish. The petri dish holding the silicon wafter was ke on a horizontal surface and two drops of the freshly sonicated Aqua-Dag ^® diamond seed sol were placed in the middle of one 1 cm x 1 cm side of th silicon substrate. Utilizing the stainless steel spatula and a see-saw tilting of the petri dish the sol was uniformly coated on one 1 cm x 1 c side of the silicon substrate. The coating was dried first at room temperature in a dust-free cabinet and then in an oven at 80 ^* C, as described in Example 1. The microwave plasma assisted chemical vapor deposition system

(MPCVD) described in detail in Example #1 and shown in Figure 9 was used this example. The silicon substrate covered with the dried sol was plac on a substrate holder 8 mounted on the quartz/stainless steel rod 12 whi is inserted into the quartz tube reactor at its bottom. The multiport

metallic adaptor 26 was properly clamped for a vacuum tight seal. Initially the substrate holder 8 was kept about 1 cm below the level of t microwave cavity 6. The exhaust valve 10 was opened and a gas flow rate about 90 seem of ultrahigh purity hydrogen was established through the reactor. The pressure was adjusted and raised from about 0.1 torr to abo 20 torr and the microwave power was switched on to produce a plasma in the reactor. The pressure was raised to about 90 torr and the substrate holde was gradually raised into the microwave cavity level, in about 10 minutes. The microwave power level from the generator 21, the tuner 18 and the tuning short 7 were simultaneously adjusted to confine uniformly the plas to the substrate/substrate holder and to adjust the temperature of the substrate, as indicated by the optical pyrometer 2, to about 950 ^* C. The reflected microwave power as indicated by the forward/reflected power mete 19 was reduced to a minimum value in the course of these finer adjustments At this point a flow of gas comprising about 10% methane, balance ultrahig purity hydrogen was switched on at a flow rate of about 10 seem to achieve a net methane content of about 1% in hydrogen and a total gas flow rate of about 100 seem. The stub-tuner 18, tuning short 7 and microwave power wer further fine turned to achieve an indicated temperature of about 990"C at the substrate. The gas pressure, gas flow rates and temperature of the substrate were maintained for about 6 hours.

The microwave power was then gradually reduced, in about 5 minutes, to zero and the system was allowed to cool to about room temperature. The methane supply was switched off. After about 20 minutes, air was introduced into the reactor and the substrate removed from the holder for optical microscopic examination, followed by SEM, XRD and Raman spectrum characterization, as detailed in Example 1.

The SEM photographs, x-ray diffraction lines and Raman spectra all showed the presence of polycrystalline diamond on the silicon substrate. Specifically, Figure 23 is an SEM photomicrograph taken at about 620X of the material formed in this Sample. Figure 24 is an x-ray powder diffraction pattern of the material formed in this Sample. Figure 25 is a Raman Spectrum of the material formed in this Sample.

Sampl e B

The steps set forth in Sample A were repeated essentially except th no methane gas was introduced into the reacotr. A total ultrahigh purity hydrogen gas flow rate of about 100 seem was maintained throughout the reaction. SEM photographs, XRD diffraction lines and Raman spectra were obtained, as detailed in Example 1, to confirm the formation of polycrystalline diamond on the silicon substrate.

Example 4 This Example demonstrates that many variations of the process parameters set forth in Example 3, Samples A and B, can be systemically varied and still lead to the formation of diamond in accordance with the present invention.

Table II sets forth the various materials and process conditions which have been varied and have produced diamond in accordance with the present invention.

TABLE II

Selected illustrative samples which follow illustrate some of the many possible changes in parameters.

Sample A This example demonstrates a method of using a polymer, specifically phenol-formaldehyde resin, as a non-vapor starting material precursor source of solid carbon. First, the polymer was heated at about 500T for about 10 hours in a nitrogen atmosphere to form a glassy carbon precursor About 0.5 g of the glassy carbon precursor was mixed with about 0.025 g o diamond seeds having an average particle size of about < 1 μm (supplied b Johnson Matthey) . A solution containing about 4 ml of deionized water an about 1 ml of ethanol was added to the glassy carbon precursor/diamond seeds mixture. This diphasic mixture was dispersed by ultrasonication fo about 3 minutes. Several drops of the diphasic sol was spread on a 1 cm 1 cm side of a cleaned silicon substrate (prepared substantially as set forth in Example 1) having a thickness of about 0.2 mm to form a layer an dried at about 80 ^* C for several hours in an air atmosphere oven. Essentially the same process as used in Example 3, Sample B for processin was carried out. Excellent Raman and XRD data proved the formation of diamond.

Sample B

About 0.5 gram of a commercial glassy carbon source material (obtained from Tokai Carbon Co. Ltd., Japan, Grade GC-20) was mixed with about 0.025 g of diamond seeds having an average particle size of about < μm (purchased from Johnson Matthey) using a pestle and mortar. The whole mixture was transferred to a clean glass test tube. A mixture of solvent containing about 2 ml of deionized water, about 2 ml of ammonium hydroxid and about 1 ml of ethanol were added to the glassy carbon/diamond seed mixture. The mixture was then dispersed utilizing an ultrasonic bath for about 3 minutes. About two drops of the sol were placed on one side of a silicon substrate measuring about 1 cm x 1 cm (prepared and cleaned essentially as described in Example 1) and spread evenly thereon (as described in Example 1) to form a layer, and the silicon substrate was

dried at about 80 ^β C for about 2 hours in an air atmosphere oven. Essentially the same process described in Example 3, Sample B was used to form the diamond. Excellent Raman and XRD data were obtained, thus provi the conversion of diamond seeded glassy carbon into diamond.

Sample C

A carbon source material comprising an about 4 gram sample of Aqua- Dag ^® E colloidal graphite (Acheson Colloids Company) was placed into a 50 ml Nalgene ^® beaker (purchased from Fisher Scientific). About 0.05 gram o diamond seeds (Johnson Matthey) having an average particle size of about lμ were added to the Nalgene® beaker. About 10 ml of deionized water, having a resistivity of about 4 M ohms, was added to the Nalgene ^® beaker and the contents of the beaker were stirred utilizing a stainless steel spatula which had been thoroughly cleaned with deionized water and dried an air atmosphere oven at about lOO'C. The contents of the Nalgene ^® beak were then subjected to ultrasonication for about three minutes in order t disperse the particles to produce a diphasic sol. Two drops of the solution were put on one side of a silicon substrate measuring about 1 cm 1 cm (prepared and cleaned essentially as described in Example 1) and spread evenly thereon (as described in Example 1) to form a layer, and th substrate was dried in an oven kept at about 80'C for about 2 hours. The silicon substrate coated with the diphasic sol was placed onto a graphite plate and into the reaction chamber of an Astex system microwave plasma assisted chemical vapor deposition reactor (purchased from Applied Scienc and Technology Inc., Woburn, MA). Essentially the same processing steps set forth in Example 9 were followed, except that the temperature of the graphite plate was maintained at about 400 ^* C and the process time was abo 20 hours. Excellent Raman and XRD data proved the conversion to diamond.

Sample D

A carbon source material comprising about 4 grams of AQUQ-DAG ^® E colloidal graphite (Acheson Colloids Company) was placed into a 50 ml Nalgene ^® beaker (purchased from Fisher Scientific). About 0.05 gram of diamond seeds (Johnson Matthey) having an average particle size of about

lμ were added to the Nalgene ^® beaker. About 10 ml of deionized water, having a resistivity of about 4 M ohms, was added to the Nalgene ^® beaker and the contents of the beaker were stirred utilizing a stainless steel spatula which had been thoroughly cleaned with deionized water and dried i an air atmosphere oven at about lOO'C. The contents of the Nalgene ^® beak were then subjected to an ultrasonic bath for about three minutes in orde to disperse the particles to produce a diphasic sol. The solution was dried overnight at about 80 ^* C in an air atmosphere oven. The diphasic dried gel powder was removed from the beaker and ground using a mortar an pestle. Then the powder was compacted into pellets measuring about 2 mm thick and 10 mm in diameter. One pellet was placed onto the graphite holder in the MPCVD system shown in Figure 9. Essentially the same processing steps used in Example 3, Sample B were followed, except that th temperature of the sample was maintained at about 1500 ^* C for about 24 hrs and the pressure was maintained at about 250 torr. Excellent Raman and X data proved the conversion to diamond.

Sample E

Both processes described in Example 3, Samples A and B were repeated with the difference that instead of diamond powder as the seed material, very fine powder samples of nickel, copper, molybdenum, platinum and palladium were used as the seed material and/or seed material precursor. Good formation into diamond crystals was confirmed by SEM, Raman and XRD characterization. Figures 26-28 are representative SEM photomicrographs of material formed utilizing copper, nickel and molybdenum powders, respectively, as the seeds in combination with a carbon source material comprising AQUA-DAG E Colloidal graphite. The photomicrographs were taken at magnifications o 750X, 1500X, and 500X, respectively.

Sample F

The process described in Example 3, Sample B was repeated with the difference being that instead of diamond powder as the seed material, abou 0.05 gram of very fine β SiC (cubic phase) having an average particle

diameter of about 1 μm (purchased from Johnson Matthey) was used as the seed material. The β SiC was mixed with about 5 grams of AQUA-DAG ^® E colloidal graphite. The processed substrate indicated a good conversion into diamond crystals.

Sample G

Essentially the same processes set forth in Example 3, Samples A an B were used, except that instead of ultra high purity W^ . and ultrahigh purity hydrogen and methane, a vapor comprising about 80% H ₂ 0 and 20% CH3 was utilized. The processed substrates indicated a good conversion into diamond crystals as shown by SEM, Raman and XRD characterization.

Example 5

A seed material comprising about ten percent by weight of fine diamond powder having an average particle diameter of about 2 μm (supplie by Warren Diamond Powder Company) was mixed thoroughly a with carbon blac source material and about 0.5% by weight of PVA binder to form a paste. The paste was dried in an air atmosphere oven at about 80 ^* C for about 2 hours and then at about 130 ^* C for about 10 minutes and then pressed into die to form small right cylinders having a diameter of about 1/4 inch and thickness of about 1/8 inch. In addition, the paste was pressed to about mm thick tablets. One tablet was diced to form an about 2 mm x 2 mm x 2 die. The die, one tablet and one right cylinder were slowly raised (over about one hour) into the plasma zone of the microwave reactor described i Example 1, and shown in Figure 9. This caused all the fluids and polymer binders to burn out slowly. The samples were reacted at about 950 ^β C for about 10 hours, all other reaction conditions were substantially the same as described in Example 1. After cooling, the samples were examined by XRD, Raman and SEM. The samples were converted essentially to nearly pur diamond with several micron-sized crystals.

Exampl e 6

This Example demonstrates a further method for forming diamond according to the present invention by utilizing a microwave plasma assist CVD reactor. The following materials were added to a 125 ml glass beaker: about 1.8 grams of a carbon powder source material (VULCAN XC-72R Cabot Corporation, Boston, MA) having an average particle size of about 30 nm; about 0.2 gram of diamond seeds (Johnson Matthey, Ward Hill, MA) having a average particle size of less than about 1 μm; about 50 ml of a solvent containing a mixture of about 70% by volume 1, 1, 1 tricholroethane and about 30% by volume 2-propanol (Aldridge, Milwaukee, MI), 99+% purity. T contents of the beaker were stirred by hand utilizing a glass rod which previously was thoroughly cleaned with deionized water and dried. About 0.1 grams of a binder (Du Pont 5200) was added to the glass beaker. The glass beaker and its contents were subjected to an ultrasonic bath

(Ultrasonics, L&R Manufacturing Company, Kearny, NJ) for about 2 minutes. A molybdenum substrate and a silicon substrate each measuring about 1.0 cm x 1.0 cm and having a thickness of about 0.02 cm were cleaned in t following manner. Two 50 ml Pyrex ^® glass beakers were thoroughly cleaned with deionized water and then acetone and dried in an air atmosphere oven at about 100'C for about 3 hours. Then about 25 ml of high purity aceton was placed into each 50 ml Pyrex® glass beaker. Utilizing a clean, fine tweezer, each substrate was placed into a separate beaker and submerged in the acetone. The beakers containing the acetone and the substrates were placed into an ultrasonic bath for about 3 minutes. After about 3 minutes the glass beakers were removed from the ultrasonic bath and the acetone w removed from each beaker. About 20 ml of isopropanol were placed into eac beaker and the substrates were submerged into the isopropanol. The beake containing the isopropanol and the substrates were placed into the ultrasonic bath for about 3 minutes. The beakers were then removed from the ultrasonic bath and the substrates were removed from the beakers and dried at about room temperature.

Several milliliters of the carbon source/diamond seed mixture were removed from the 125 ml glass beaker utilizing a disposable plastic

transfer pipet (Aldridge, Milwaukee, MI). Two drops (i.e., about 0.2 ml) of the carbon/diamond seed mixture were applied to about the center of o of the sides of each substrate, said substrates measuring about 1.0 cm x 1.0 cm. Each substrate was then slightly tilted in all directions in or to spread the carbon/source diamond seed mixture over substantially the entire 1.0 cm x 1.0 cm side of each substrate. A temperature of about 100°C was established in an air atmosphere oven and each substrate was placed into the oven and allowed to dry substantially completely.

The same MPCVD described in Example 1 and depicted in Figure 9 was utilized in this Example.

The coated silicon substrate was placed into the substrate holder with the coated side facing up. A gas flow rate of about 80 seem of ult pure hydrogen and about 20 seem of a mixture of 10% methane, balance ult pure hydrogen (i.e., a total gas flow rate of about 100 seem) was established through the MPCVD. A reactor pressure of about 90 torr was established. The microwave power was turned on and the temperature of th coated silicon substrate was raised from about room temperature to about 975'C in about 20 minutes, thus producing a plasma. The gas flow rate, reactor pressure and temperature were maintained for about 5 hours. Afte about 5 hours, the microwave power was gradually reduced in about 10 minutes and then turned off; the substrate was allowed to cool to about room temperature; the pressure within the reactor was increased to ambie and the gas flow was interrupted completely. The silicon substrate was then removed from the substrate holder. The coated molybdenum substrate was subjected to substantially the same reaction conditions as the coated silicon substrate.

The control settings of a Raman spectrograph (ISA RAM U-1000) were set as follows: laser wave length = 514.532 nm; laser power = 40 mw; sli == 200 μm; increments - 1.00 cm ^"1 ; magnification * 40X; and NB scans = 1. The coated side of each substrate was subjected to Raman spectrosc and a very sharp Raman line around 1332 cm ^"1 was obtained from the coati on each sample. This value corresponds to diamond crystals only. The spectrum also showed the presence of some residual graphitic carbon. Th

Raman spectrums of the samples on the silicon and molybdenum substrates a shown in Figures 10 and 11, respectively.

Also, scanning electron microscopy pictures were taken from the surface of the silicon and molybdenum substrate, as shown in Figures 12 a 13, respectively. Figures 12 and 13 demonstrate the polycrystalline morphology of the diamond coatings, their pure crystalline structure and good nucleation density. An environmental SEM (electronscan ES-30) and a high vacuum type SCM (ISI DS 130) were used for this purpose.

Finally, the coatings were analyzed using x-ray diffraction and the x-ray diffraction patterns showed a peak at d = 2.058 Angstrom, which corresponds to diamond crystals, thus further confirming the quality of t diamond layer formed on each substrate.

Example 7 This Example demonstrates a further method for forming diamond according to the present invention. Specifically, this Example utilizes hydrogen/oxygen flame technique.

About 0.64 grams of AQUA-DAG® E colloidal graphite carbon source material (purchased from Ted Pella Inc., Tustin, CA) was placed into a 50 ml Nalgene ^® plastic beaker (Fisher Scientific, Pittsburgh, PA). About

0.025 grams of diamond seeds (Johnson Matthey) having an average particle size of less than about 1 μm and about 10 ml of deionized water were adde to the Nalgene ^® plastic beaker. The contents of the beaker were stirred hand utilizing a stainless steel spatula which had previously been thoroughly cleaned with deionized water and dried in an air atmosphere ov at about lOO'C. The Nalgene® plastic beaker containing the AQUA-DAG ^® E source material/diamond seed solution was subjected to an ultrasonic bath for about 3 minutes to sufficiently disperse the particles to form a diphasic solution. About 3 drops of 20 weight percent polyvinyl alcohol binder

(PolySciences, Inc., Warrington, PA), having a weight of about 0.21 gram, were added to a glass test tube. The binder was dissolved by adding abou 3 ml of deionized water and then placing the test tube in an ultrasonic bath and subjecting the contents of the glass test tube to an ultrasonic

bath for about 2 minutes. After about 2 minutes, the test tube was remov from the ultrasonic bath and the contents of the test tube were added to the AQUA-DAG® E source material/diamond seed diphasic solution contained the Nalgene ^® plastic beaker. The Nalgene® plastic beaker and its content were then subjected to an ultrasonic bath for about 2 minutes. After abo 2 minutes, the Nalgene® plastic beaker was removed from the ultrasonic ba and the diphasic solution was transferred to a glass beaker. The glass beaker and its contents were then placed into an air atmosphere oven at a temperature of about 100'C for about 2 hours. After about 2 hours and before the diphasic solution dried completely, the glass beaker was remov from the oven and small substantially spherical balls having an average diameter of about 1-2 mm were made by hand from the diphasic mixture. Th substantially spherical balls were then placed into a clean petri dish an the petri dish containing the spherical balls was placed into the 100 ^β C a atmosphere oven for about 3 hours in order to dry the spherical balls substantially completely.

An about 1 cm diameter and 0.2 cm deep cavity was machined from a piece of high quality graphite in order to form a cavity for housing the spherical balls. A total of 6 spherical balls were placed into the cavit and a gas mixture of H2/O2 was used to create a flame through a burner tube. The H2/O2 ratio was adjusted in such a way that the flame would no force the spherical balls out of the cavity. The flame was directed towards the cavity so that the inner blue portion of the flame was concentrated on the spherical balls. It was noted that the spherical bal became white hot. After subjecting the spherical balls to the flame for about 4 minutes, the flame was removed from the spherical balls. The spherical balls were allowed to cool to room temperature and were thereafter ground using an agate mortar and pestle.

The ground spherical balls were then subjected to x-ray powder diffraction and the results are shown in Figure 14. Figure 14 shows the formation of a diamond phase apart from the graphite peak.

Figure 15 shows the results of x-ray powder diffraction analysis of the spherical balls before being subjected to the above flame treatment.

As shown in Figure 15, the x-ray powder diffraction pattern of the spherical balls before the flame treatment shows only the graphite peak.

Figures 16a and 16b show the results of scanning electron microgra (SEM) of the spherical balls after the above flame treatment. An environmental SEM (electroscan ES-30) was used for this purpose.

Example 8

A seed material comprising approximately 5% (solids by wt.) of fin diamond powder (average particle size < 1 μm, purchased from Johnson Matthey) was added to and dispersed within a sample of an AQUA-DAG ^® E colloidal graphite carbon source. The mixture was spread onto a silicon wafer (prepared and cleaned essentially as described in Example 1) with spatula and allowed to dry substantially completely for about 12 hours a about room temperature in a desiccator. The coated wafer was then introduced into a standard microwave Astex reactor (described in Example 9). The reactor was evacuated to about 0.001 mm Hg and the pressure was then raised to about 20 torr utilizing ultrahigh purity hydrogen gas. A gas flow rate, comprising about 99% ultrahigh purity hydrogen and about 1 methane, of about 100 seem was established through the reactor. The microwave power from the microwave power generator was turned on and the temperature of the graphite substrate was raised from about room temperature to about 950'C. The microwave power generator was tuned to produce a plasma in the reaction chamber and the coated wafer was slowly moved into the plasma. After reaction for about 20 hours the wafer was removed from the reactor and characterized by optical microscopy, SEM microscopy, XRD, and Raman spectroscopy. The formed body was about 25 μ thick and was essentially completely converted to diamond, as shown by th SEM photomicrograph of Figure 6 and the Raman pattern of Figure 8. The above steps were repeated to result in sequential additions of 25 μ (fina diamond thickness) layers, thus resulting in the build up of thicker freestanding films.

Example 9

This example demonstrates a method for forming diamond fibers according to the method of the present invention.

A first carbon source material comprising an about 4 gram sample of AQUA-DAG ^® E Colloidal graphite (Acheson Colloids Company) was placed into 50 ml Nalgene ^® beaker (purchased from Fisher Scientific). About 0.05 gra of a diamond seed material (purchased from Johnson Matthey, Ward Hill, MA having an average particle size of about < 1 micron, and a second seed material comprising about 0.1 gram of -120 mesh nickel (purchased from Johnson Matthey, Ward Hill, MA), were added to the Nalgene ^® beaker, 10 ml of deionized water, having a resistivity of about 4 M ohms, was added to the Nalgene ^® beaker and the contents of the beaker was stirred utilizing stainless steel spatula which had been thoroughly cleaned with deionized water and dried in an oven at about lOO'C. The contents of the Nalgene ^® beaker was then subjected to an ultrasonic bath for about three minutes i order to disperse the particles to produce a triphasic solution.

A second carbon source material comprising a small bundle of carbon fibers (procured from the United States Navy and identified as "Type AS4 12K") having a length of about 1" and an average fiber diameter of about microns, and weighing about 0.0004 gram were dipped into the solution suc that substantially all of the surfaces of each carbon fiber was coated wi the triphasic solution. The coated fibers were then dried overnight at room temperature.

A boron nitride holder for holding the coated fibers was prepared b machining an about 1/8 inch diameter cylindrical hole into a boron nitrid rod (purchased from Union Carbide, Cleveland, OH) having a diameter of about 1" and a length of about 3/8". The dried bundle of fibers was plac into the cylindrical hole and the boron nitride holder was placed onto a graphite plate. The graphite plate and boron nitride holder containing t bundle of fibers were placed into the reaction chamber of an Astex System microwave plasma assisted chemical vapor deposition reactor (purchased fr Applied Science & Technology, Inc., Woburn, MA).

Figure 29 is a schematic view of the Astex System microwave plasma assisted chemical vapor deposition reactor which was utilized in this

example. Table III provides in tabular form a list of the different components of the Astex System shown in Figure 29, wherein the reference numerals utilized in Figure 29, are cross referenced to the different components of the Astex System.

TABLE III

Reference

Numerals Component Parts

50 Load

51 Circulator

52 Microwave Source

53 Power Supply 54 Mass-fl ow Control l ers

55 Gas Cylinders

56 3-Stub Tuner

57 Antenna Probe Adjustment

58 Coaxial Transition 59 Tuner

60 Reactor Cavity

61 Plasma

62 Substrate

63 Heater 64 Temperature Control Gauge

65 Optical Window

66 Pyrometer

67 Throttle Valve

68 Vacuum Pump 69 Substrate Heater Raise-Lower System

The reactor 60 was evacuated to about 0.001 mm of Hg and the pressur was then raised to about 20 torr utilizing ultra high purity hydrogen gas. A hydrogen gas flow rate of abut 100 SCCM was established through the reactor 60. The microwave power from the microwave power source 52 was turned on and the temperature of the graphite substrate 62 was raised from about room temperature to about 800 ^* C. The microwave power source 52 was tuned to produce a plasma 61 in the reaction chamber 60. The gas flow rate, pressure and temperature were maintained for about 20 hours. After about 20 hours, the microwave power was gradually reduced and then turned off; the substrate temperature was reduced to about room temperature; the pressure within the reactor was increased to ambient; and the gas flow rat

was interrupted completely. The graphite plate, boron nitride holder and bundle of fibers were removed and the fibers were removed from the boron nitride holder.

The fibers were analyzed utilizing a Raman Spectrograph (Model ISA RAM U-1000). The control settings of the Raman spectrograph were set as follows: laser wavelength - 514,532 nm; laser power - 200 mm; slits = 200 μm; increment = 1.00 cm ^"1 ; magnification - 40x; NB scans - 1.

The fibers were subjected to Raman spectroscopy and a very sharp Raman line of about 1325 cm ^"1 was obtained, which corresponds to diamond crystals only. SEM photomicrograph taken at 604x of one of the fibers is shown in Figure 30. Showing part of the fibers are converted to diamond which were exposed to the plasma and part of them are not converted. The Raman spectra of the converted part is shown in Figure 31.

Example 10

This example demonstrates a method for forming diamond fibers according to the method of the present invention.

A seed material precursor comprising about 0.66 gram nickel nitrate hexa hydrate (Ni(NU3)2.6H2θ) (purchased from Aldrich Chemical Company) wa dissolved in about 1 ml of deionized water. A carbon source material comprising a small bundle of carbon fibers (procured from the United Stat Navy and identified as "Type AS4 12K") having a length of about I" and an average fiber diameter of about 10 microns, were dipped into the solution such that substantially all of the surfaces of each carbon fiber was coat with the solution. The coated fibers were then dried overnight at room temperature.

A boron nitride holder for holding the coated fibers was prepared b machining an about 1/8 inch diameter cylindrical hole into a boron nitrid rod (purchased from Union Carbide, Cleveland, OH) having a diameter of about 1" and a length of about 3/8". The dried bundle of fibers was plac into the cylindrical hole and the boron nitride holder was placed onto a graphite plate. The graphite plate and boron nitride holder containing t bundle of fibers were placed into the reaction chamber of an Astex System

microwave plasma assisted chemical vapor deposition reactor (purchased fr Applied Science & Technology, Inc., Woburn, MA).

The reactor was evacuated to about 0.001 mm of Hg and then a reacto pressure of about 20 torr was established utilizing ultra high purity hydrogen gas. The temperature of the graphite plate was raised to about 500 ^* C and held at this temperature for about 5 hours. After about 5 hour the temperature was increased to about 880 ^* C. A hydrogen gas flow rate o about 100 SCCM was established through the reactor. The microwave power from a microwave power generator was turned on and tuned to produce a plasma in the reaction chamber. The gas flow rate, pressure and temperature were maintained for about 20 hours. After about 20 hours, th microwave power was gradually reduced and then turned off; the substrate temperature was reduced to about room temperature; the pressure within th reactor was increased to ambient; and the gas flow rate was interrupted completely. The graphite plate, boron nitride holder and bundle of fiber were removed and the fibers were removed from the boron nitride holder.

Figure 17 is an SEM photomicrograph taken at about 240X of one of t fibers in this example.

Example II

This example demonstrates a method for forming diamond fibers according to the method of the present invention.

A seed mateial comprising about 0.05 gram of -120 mesh nickel powde (purchased from Johnson Matthey, Ward Hill, MA) and about 2 ml of deioniz water were placed into a 50 ml NALGENE ^® beaker (purchased from Fisher

Scientific). The nickel powder was dispersed by subjecting the beaker an its contents to an ultrasonic bath for about 3 minutes.

A carbon source material comprising a small bundle of carbon fibers (procured from the United States Navy and identified as "Type AS4 12K") having a length of about 1" and an average fiber diameter of about 10 microns were dipped into the sol such that substantially all of the surfaces of each carbon fiber was coated with the nickel sol. The coated fibers were then dried overnight at about room temperature.

Essentially the same process used in Example #9 was used, except th the reaction temperature was about 900 ^* C and the reaction time was about hours.

The fibers were subjected to Raman spectroscopy and, as shown in Figure 18, a very sharp Raman line around 1333cm ^"1 was obtained.

Figure 19 is an SEM photomicrograph taken at about 353X of a sample of the fibers produced in this example. Example 12

This example demonstrates a method for forming diamond fibers according to the method of the present invention.

A first carbon source material comprising an about 4 gram sample of AQUADAG ^® E Colloidal graphite (Acheson Colloids Company) was placed into 50 ml NALGENE® beaker (purchased from Fisher Scientific). About 0.05 gra of diamond seeds (purchased from Johnson Matthey, Ward Hill, MA), having average particle size of <1 micron, were added to the NALGENE ^® beaker.

About 10 ml of deionized water, having a resistivity of about 4 M ohms, w added to the NALGENE ^® beaker and the contents of the beaker were stirred utilizing a stainless steel spatula which had been thoroughly cleaned wit deionized water and dried in an oven at about lOO'C. The contents of the NALGENE ^® beaker were then subjected to an ultrasonic bath for about three minutes in order to disperse the particles to produce a diphasic solution

A second carbon source material comprising a small bundle of carbon fibers (procured from the United States Navy and identified as "Type AS4 12K") each having a length of about 2.5 cm and an average fiber diameter about 10 microns were dipped into the diphasic solution such that substantially all of the surfaces of each carbon fiber was coated with th diphasic solution. The coated fibers were then dried overnight at room temperature.

Essentially the same process used in Example 9 was used, except tha the reaction temperature was about 900 ^* C and the reaction time was about hours.

The fibers were analyzed utilizing a Raman Spectrograph (Model ISA RAM U-1000). The control settings of the Raman spectrograph were set as

follows: laser wavelength = 514.532nm; laser power=200mw; slits=200μm; increment=1.00cm ^" , magnification=40x; NB scans=l.

The fibers were subjected to Raman spectroscopy and a very sharp Raman line around 1325cm ^"1 was obtained, which corresponds to diamond crystals only.

Figure 20 is a Raman Spectrum of the material formed in this exampl Figures 21 and 22 are SEM photomicrographs taken at about 347X and 490X, respectively, of the fibers produced in this example.

Example 13

This example demonstrates a method for forming diamond fibers according to the method of the present invention.

A seed material comprising about 0.03 gram of diamond powder and about 2 ml of deionized water were placed into a 50 ml NALGENE ^® beaker (purchased from Fischer Scientific). The diamond powder was dispersed by subjecting the beaker and its contents to an ultrasonic bath for about 3 minutes.

A small bundle of carbon fibers (procured from the United States Na and identified as "Type AS4 12K") each having a length of about 2.5 cm an an average fiber diameter of about 10 microns, were dipped into the solution such that substantially all of the surfaces of each carbon fiber was coated with the sol. The coated fibers were then dried overnight at room temperature.

Essentially the same process used in Example 9 was used. The fibers were analyzed utilizing a Raman Spectrograph (Model ISA RAM U-1000). The control settings of the Raman spectrograph were set as follows: laser wavelength = 514.532nm; laser power=200mw; slits=200μm; increment=1.00cm ^_1 ; magnification=40x; NB scans=l.

The fibers were subjected to Raman spectroscopy and a very sharp Raman line around 1335cm ^"1 was obtained.

Example 14

Figure 32 is a schematic view of a hot filament type diamond deposition/conversion system which was utilized in this example. Table I

provides in tabular form a list of the different components of the system shown in Figure 32, wherein the reference numerals utilized in Figure 32 are cross referenced to the different components of the system.

In the hot filament type diamond deposition/conversion system, the active species are produced by bringing the hydrogen and carbon containing vapor (in this example methane gas, which is used in combination with the solid carbon source material in this example) in contact with a very hot filament structure (around 2000 ^* C). The substrate material, a dried-up so of different types of carbon source seeded with diamond seeds, metallic or nonmetallic seed powders, was kept very close to the hot filament to interact with the active species to form diamond crystals.

Referring to Figure 32 the hot filament reactor system comprises a carburized tantalum wire heater 106 in the form of a circular gauze which

was heated by R.F. induction heating by R.F. coil 105 connected to a radi frequency (450 kHz) power generator (10 KW) 109. The coil 105 is placed outside the quartz tube reactor 104 close to the position of the tantalum wire heater grid 106. A silicon substrate material was prepared essentially as described Example 3, Sample A. The substrate was placed on the substrate holder 10 and raised into the reactor tube 104, keeping it at about 1 cm below the hot filament 106. A gas comprisng ultrahigh purity hydrogen with 1% methane was utilized to establish a gas flow rate of about 200 seem throu the reactor and a pressure of about 30 torr. The flow rate and pressure were maintained by the automatic flow and pressure controllers. The RF power from the radio-frequency generator 109 was adjusted to achieve a temperature of about 2200'C at the tantalum filament grid 106 as indicate by the optical pyrometer 103. The position of the RF coil 105 was also adjusted to achieve a substrate temperature of about 950 ^* C as indicated b the thermocouple 111 attached to the bottom of the substrate through a ho in the substrate holder.

The gas flow rate, gas pressure and temperatures of the tantalum filament and substrate were maintained for a period of about 6 hours afte which the heating power was switched off to cool down the reacted substrate. The substrate was then characterized by Raman, SEM, and XRD which showed the presence of a good polycrystalline diamond coating.

Example 15 This example demonstrates a method for forming diamond by utilizing an internal atomic hydrogen source by a non-plasma assisted conversion.

Specifically, a carbon source material comprising about 5 grams of AQUA-DAG ^® E colloidal graphite (Acheson Colloids Company, MI) was weighed in a clean 30 ml Pyrex ^® glass beaker. To this AQUA-DAG ^® E was added a se material comprising about 0.25 g of diamond powder (particle size about 2 micron, Type 300S supplied by Warren Diamond Powder Co. Inc.). While stirring this with a cleaned stainless steel spatula, about 15 ml of deionized water was added. This mixture was given ultrasonic agitation f about 15 minutes in an ultrasonic bath (manufactured by Geoscience

Instruments Corporation, NY). The diphasic sol was poured into a clean glass petri dish. The petri dish was maintained in an air atmosphere ove kept at about 80"C for about two hours and then in an air atmosphere oven at about 130 ^* C for about 10 minutes to substantially completely dry the sol. The flakes of AQUA-DAG® E source material seeded with diamond powde were then ground into a fine powder (less than 400 mesh) in an agate mort and pestle. About 2 grams of this powder was mixed with a substantailly equal quantity of zirconium hydride powder (-325 mesh, 99%, supplied by Alfa, Johnson Matthey Catalog Company, Inc., MA). This powder was ball milled for about 2 hours to form a homogeneous mixture and then pressed into about 1/4 inch diameter tablets using a stainless steel die, at a pressure of about 6.9 x 10 ⁵ Pa.

Two of these tablets were placed into a small graphite crucible, having a diameter of about 2.45 cm and a height of about 2 cm, and covere with a graphite lid. The tablets were then covered with a small quantity of the zirconium hydride powder. The crucible was provided with six, 1 m wide and 1 mm deep grooves at the top to permit a slow diffusion of gases into and out of the crucible even when covered with the lid.

As shown in Figure 7, the crucible was placed into an alumina boat 202 and the alumina boat was placed in the middle of an about 2 inch diameter alumina tube furnace 205 (supplied by Lindberg Co). The ends of the tube furnace are closed with metallic adaptors with 0-rings and additionally, have 1 cm diameter tubes for inlet and outlet of any gas. The furnace inlet 200 was connected to an ultra pure hydrogen gas cylinde through a precision float valve. The outlet tube 206 of the furnace was connected through a bubbler to an exhaust hood. After flowing the ultra high purity hydrogen for about 20 minutes through the furnace tube 205 to displace the air inside substantially completely, the power to the furnac was switched on. The furnace temperature was raised from about room temperature to about 850 ^* C in about 3 hours. The temperature was then raised to about 935 ^* C in about 3 hours. After reaching about 935'C, the temperature was increased to about 945 ^* C in about 24 hours and then raise to about 970 ^* C in about 6 hours. The furnace temperature was then increased to about 1100'C and then cooled to about room temperature in

about 8 hours. The hydrogen flow was decreased to about 60 bubbles/minut at the start of the heating cycle and maintained at this rate throughout the process. At the end of the process, the alumina boat with graphite crucible was withdrawn from the furnace. The tablets of processed materi were taken for x-ray diffraction analysis.

The x-ray diffraction spectrum, shown in Figure 33, showed a large sharp XRD peak at d - 2.056 angstrom which is typical of diamond. The XR taken for the powder before the process indicated the presence of a very small quantity of diamond seed as shown in Figure 34. This indicates a bulk conversion of carbon into diamond.

Example 16

The example demonstrated a non-plasma method of forming diamond utilizing glassy carbon as a solid carbon source. Specificially, the carbon source material comprising glassy carbon was prepared by heat treatment of phenol-formaldehyde resin as described Example 4, Sample A.

About three grams of the glassy carbon fine powder were weighed in clean 30 ml Pyrex ^® glass beaker. To this was added about 0.3 gram of diamond seed (less than 1 micron size, natural, 99.9% supplied by Johnson Matthey, their Catalog No. 13401), and about 0.305 grams of a PVA solutio (5% PVA in deionized water). About 10 ml of deionized water, of resistivity better than 7 M ohm, was added and stirred with a clean stainless steel spatula. This sol was subjected to ultrasonic cleaning i an ultrasonic bath, (a product of Geoscience Instruments Corporation, NY) for about 30 minutes. This homogenized sol was poured into a clean 10 cm diameter petri dish. The dish and its contents was placed in a dust-free cabinet (kept at about 50'C) for about 12 hours. The dish and its conten was then transferred to an air atmosphere oven at about 130 ^* C and kept at this temperature for about 15 minutes to substantially completely dry out the deionized water. With a sharp and clean stainless steel blade small platelets of precursor material of about 5 mm x 5 mm were cut out and put in a clean graphite crucible and put in an alumina boat.

The boat carrying the crucible was placed in the middle of the conventional controlled atmosphere alumina tube furnace (Lindberg Company) described in Example 15 and shown in Figure 7. An atmosphere of ultrahigh purity hydrogen was created in the furnace and a flow of about 60 bubbles/minute was adjusted and maintained throughout the process using a precision-leak float-valve. Substantially the same heating schedule used in Example 15 was used in this Example. Upon reaching room temperature, the boat with the crucible containing the processed material was removed from the furnace and the processed material was subjected to x-ray diffraction analysis. Figure 35 shows very clean and sharp crystalline phase diamond lines at 2.059 and 1.260. The relatively low count of the same lines in Figure 36 showing XRD of the precursor material before processing indicates that the process has increased the diamond content appreciably.

Example 17

This example demonstrates a method for forming diamond by utilizing an internal atomic hydrogen source by a non-plasma assisted conversion.

The process described in Example 15 was repeated with the differece that instead of ultrahigh purity hydrogen, ultrahigh purity argon was used to supply the atmosphere inside the furnace. The processed material showe a good conversion into diamond crystals.

As a further aspect of the invention it should be noted that different inert gases in combination with different seed materials, carbon source materials, and internal sources of atomic hydrogen may produce different morphologies of diamond crystals and give different conversion rates.