CHEMICAL VAPOR DEPOSITION PROCESS FOR DEPOSITING A MIXED METAL OXIDE COATING AND THE COATED ARTICLE FORMED THEREBY

BACKGROUND OF THE INVENTION

This invention relates in general to a chemical vapor deposition (CVD) process for depositing a mixed metal oxide coating. The invention also relates to the mixed metal oxide coating formed according to the CVD process.

Forming glass articles by depositing coatings on a glass substrate is known. Also, it is known to utilize a color suppression interlayer on a glass substrate to reflect and refract light to interfere with the observance of iridescence. In a two-layer color suppression interlayer, the first coating is deposited on the glass substrate and provided with a refractive indexwhich is higher than the refractive index of the glass substrate. The second coating is deposited on the first coating and is provided with a refractive index which is lower than the refractive index of the first coating and the refractive index of the glass substrate. Coatings known to be utilized as the first coating in two-layer color suppression interlayers have refractive indexes that are relatively low and fail to block sodium diffusion from the glass substrate. Thus, it would be desirable to provide a coating that could be utilized as the first coating in a two-layer color suppression interlayer that has a higher refractive indexthan the known coatings and can act as a sodium diffusion barrier.

Also, depositing a color suppression interlayer that requires two coating layers adds cost and complexity to forming the glass article. Thus, a color suppression interlayer with a reduced number of coating layers may be advantageous. As such, in certain applications, it may be desirable to deposit a coating that can be utilized as a single coating color suppression interlayer.

SUMMARY OF THE INVENTION

A chemical vapor deposition process for depositing a mixed metal oxide coating comprises providing a glass substrate, forming a gaseous mixture comprising a titanium-containing compound, a silicon-containing compound, and an oxygen-containing compound, and directing the gaseous mixture toward and along the glass substrate. The mixture reacts over the glass substrate to form the mixed metal oxide coating thereover. The mixed metal oxide coating comprises titanium oxide and silicon oxide, wherein the mixed metal oxide coating is more than 50% titanium oxide and has a refractive index of 2.2 or less.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS

The above, as well as other advantages of the process will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawing in which: FIG. 1 is a schematic view, in vertical section, of an installation for practicing the float glass manufacturing process in accordance with certain embodiments of the invention;

FIG. 2 is a sectional view of a coated glass article in accordance with an embodiment of the invention;

FIG. 3 is a sectional view of a coated glass article in accordance with another embodiment of the invention;

FIG. 4 is a sectional view of a coated glass article in accordance with yet another embodiment of the invention; and

FIG. 5 is a sectional view of a coated glass article in accordance with still another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific articles, apparatuses and processes described in the following specification are simply exemplary embodiments of the inventive concepts. Hence, specific dimensions, directions, or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless expressly stated otherwise. Also, although they may not be, like elements in the various embodiments described within this section of the application may be commonly referred to with like reference numerals.

In an embodiment, a CVD process for depositing a mixed metal oxide coating (hereinafter also referred to as the "CVD process") is provided. The CVD process will be described in connection with embodiments of a coated glass article 6, 6A, 6B, 6C. The embodiments of the coated glass article 6, 6A, 6B, 6C may be utilized in architectural glazings, electronics, and/or have automotive, aerospace and solar cell applications.

Referring now to Figs 2-5, the CVD process is utilized to deposit a mixed metal oxide coating 1 . Preferably, the mixed metal oxide coating 1 is deposited over a glass substrate 2. The mixed metal oxide coating 1 comprises titanium oxide and silicon oxide.

Preferably, the titanium oxide is titanium dioxide. More preferably, the titanium oxide is stoichiometric titanium dioxide. Titanium dioxide may be designated herein by utilizing the chemical formula Ti0 ₂ . However, the titanium oxide may be of another suitable stoichiometry. Also, in certain embodiments, the titanium oxide in the mixed metal oxide coating may be slightly oxygen deficient. When the titanium oxide is titanium dioxide, it is preferred that the titanium dioxide is in the anatase form. However, other forms of titanium dioxide may be present in the mixed metal oxide coating.

Preferably, the silicon oxide is silicon dioxide. More preferably, the silicon oxide is stoichiometric silicon dioxide. Silicon dioxide may be designated herein by utilizing the chemical formula Si0 ₂ . However, the silicon oxide may be of another suitable stoichiometry. Also, in certain embodiments, the silicon oxide in the mixed metal oxide coating may be slightly oxygen deficient.

In certain embodiments, the mixed metal oxide coating comprises 2% or more silicon oxide with the balance being primarily titanium oxide, and the mixed metal oxide preferably comprising more than 50% titanium oxide. Preferably, the mixed metal oxide coating comprises 4% or more silicon oxide. In one such embodiment, the mixed metal oxide coating comprises 10% or more silicon oxide. In another such embodiment, the mixed metal oxide coating comprises 15% or more silicon oxide. In yet another such embodiment, the mixed metal oxide coating comprises 25% or more silicon oxide. In other embodiments, the mixed metal oxide coating comprises 2 - 49% silicon oxide with the balance being primarily titanium oxide. More preferably, in these embodiments, the mixed metal oxide coating comprises 4 - 35% silicon oxide. The mixed metal oxide coating may also contain contaminants of, for example, carbon, chlorine and/or fluorine. Preferably, when the mixed metal oxide coating contains contaminants, the contaminants are provided in only trace amounts or less.

Due to the composition of the mixed metal oxide coating mentioned above, the coating exhibits photoactivity. It should be appreciated that photoactivity refers to the mixed metal oxide coating's ability to structurally degrade dirt and other organics present on the coating when the coating is exposed to ultraviolet radiation, and subsequently washed away by water. Also, as discussed herein, photoactivity will be described with reference to the mixed metal oxide coating's ability to degrade the chemical methylene blue. Preferably, the photoactivity of the mixed metal oxide coating is 500 nmol/(cm ² xhr) or more. More preferably, the mixed metal oxide coating is 1 ,000 nmol/(cm ² xhr) or more. In other embodiments, the mixed metal oxide coating is also hydrophilic.

Additionally, in certain embodiments like the ones illustrated in Figs 2-4, the mixed metal oxide coating 1 can be formed directly on a deposition surface 3 of the glass substrate 2 without the need to deposit a nucleation coating layer of, for example, silica (Si0 ₂ ) or tin oxide (Sn0 ₂ ) prior to forming the mixed metal oxide coating. In other embodiments, like the one illustrated in FIG. 5, the mixed metal oxide coating 1 may be formed over one or more previously deposited coating layers 4, 5.

A feature of the CVD process is that it allows for the formation of the mixed metal oxide coating at a commercially viable deposition rate. For example, utilizing the CVD process, the mixed metal oxide coating may be formed at a deposition rate of 5.0 nanometers per second (nm/sec) or more. More preferably, the mixed metal oxide coating is formed at a deposition rate of 10.0 nm/sec or more. In certain embodiments, the coating is formed at a dynamic deposition rate of 225 nm x m/min or more. In these embodiments, the mixed metal oxide coating can be formed directly on the deposition surface of a glass substrate or on a coating that has been previously deposited on the glass substrate. The CVD process also provides additional advantageous features. For example, the CVD process allows for the deposition of a coating layer that can be utilized in a color suppression interlayer. In one such embodiment, the mixed metal oxide coating is utilized in a two-layer color suppression interlayer. In this embodiment, the mixed metal oxide coating is deposited directly on the deposition surface of the glass substrate. In this position, the coating may act as a barrier against sodium diffusion from the glass substrate. Also, in this embodiment, the coating can be deposited so that it has a refractive index of 1.85 or more. It should be appreciated that, if the first coating layer in a two-layer color suppression interlayer has a refractive index of 1 .85 or more, the color suppression interlayer may have improved iridescence interference properties. In other embodiments, the mixed metal oxide coating may be deposited to provide a single layer color suppression interlayer. It should be appreciated that a single layer color suppression interlayer reduces the complexity and the cost required to deposit a color suppression interlayer when compared to an interlayer requiring two coating layers. In embodiments where the mixed metal oxide coating is utilized as a single layer color suppression interlayer, the mixed metal oxide coating is also deposited directly on the deposition surface of the glass substrate.

The CVD process comprises providing the glass substrate. The glass substrate comprises the deposition surface over which the mixed metal oxide coating is formed. In an embodiment, the glass substrate is a soda-lime-silica glass. However, the CVD process is not limited to a soda-lime- silica glass substrate as, in other embodiments, the glass substrate may be a borosilicate glass. Additionally, it may be preferable to utilize a glass substrate having a low iron content in practicing the process. Thus, in certain embodiments, the CVD process is not limited to a particular substrate composition.

Further, in certain embodiments, the glass substrate is substantially transparent. However, the invention is not limited to transparent glass substrates as translucent glass substrates may also be utilized in practicing the CVD process. Also, the transparency or absorption characteristics of the substrate may vary between embodiments. Additionally, the CVD process can be practiced utilizing a clear or a colored glass substrate and is not limited to a particular glass substrate thickness.

The CVD process may be carried out in conjunction with the manufacture of the glass substrate. In an embodiment, the glass substrate may be formed utilizing the well-known float glass manufacturing process. An example of a float glass manufacturing process is illustrated in FIG. 1 . In this embodiment, the glass substrate may also be referred to as a glass ribbon. However, it should be appreciated that the CVD process can be utilized apart from the float glass manufacturing process or well after formation and cutting of the glass ribbon.

In certain embodiments, the CVD process is a dynamic deposition process. In these embodiments, the glass substrate is moving at the time of forming the mixed metal oxide coating. Preferably, the glass substrate moves at a predetermined rate of, for example, greater than 3.175 m/min (125 in/min) as the mixed metal oxide coating is being formed thereon. In an embodiment, the glass substrate is moving at a rate of between 3.175 m/min (125 in/min) and 12.7 m/min (600 in/min) as the mixed metal oxide coating is being formed.

In certain embodiments, the glass substrate is heated. In an embodiment, the temperature of the glass substrate is about 1100°F (593°C) or more when the mixed metal oxide coating is deposited thereover or thereon. In another embodiment, the temperature of the glass substrate is between about 1 100°F (593°C) and 1400°F (760°C).

Preferably, the mixed metal oxide coating is deposited over the deposition surface of the glass substrate while the surface is at essentially atmospheric pressure. In this embodiment, the CVD process is an atmospheric pressure CVD (APCVD) process. However, the CVD process is not limited to being an APCVD process as, in other embodiments, the mixed metal oxide coating may be formed under low-pressure conditions.

The CVD process may comprise providing a source of a titanium-containing compound, a source of a silicon-containing compound, a source of one or more oxygen-containing compounds, and a source of one or more inert gases. Preferably, these sources are provided at a location outside the float bath chamber. Separate supply lines may extend from the sources of reactant (precursor) compounds and the one or more carrier gases. As used herein, the phrases "reactant compound" and "precursor compound" may be used interchangeably to refer any or all of the titanium-containing compound, silicon-containing compound, oxygen-containing compounds, and/or used to describe the various embodiments thereof disclosed herein.

The CVD process also comprises forming a gaseous mixture. As would be appreciated by those skilled in the art, the precursor compounds suitable for use in the gaseous mixture should be suitable for use in a CVD process. Such compounds may at some point be a liquid or a solid but are volatile such that they can be vaporized for use in the gaseous mixture. In certain embodiments, the gaseous mixture includes precursor compounds suitable for forming the mixed metal oxide coating at essentially atmospheric pressure. Once in a gaseous state, the precursor compounds can be included in a gaseous stream and utilized in the CVD process to form the mixed metal oxide coating.

For any particular combination of gaseous precursor compounds, the optimum

concentrations and flow rates for achieving a particular deposition rate and mixed metal oxide coating thickness may vary. However, in order to form a mixed metal oxide coating as is provided by the CVD process described herein, the gaseous mixture comprises the titanium-containing compound, the silicon-containing compound, and an oxygen-containing compound.

In certain embodiments, the titanium-containing compound is an inorganic titanium-containing compound. Preferably, in these embodiments, the titanium-containing compound is an inorganic, halogenated titanium-containing compound. An example of an inorganic, halogenated titanium- containing compound suitable for use in the forming the gaseous mixture is titanium tetrachloride

(TiCI ₄ ). Titanium tetrachloride is preferred because it is relatively inexpensive and it does not include carbon, which can become trapped in the mixed metal oxide coating during formation of the coating. However, the invention is not limited to titanium tetrachloride as other halogenated titanium- containing compounds may be suitable for use in practicing the CVD process.

In other embodiments, the titanium-containing compound is an organic titanium-containing compound. Preferably, in these embodiments, the titanium-containing compound is a titanium alkoxide compound. An example of a titanium alkoxide compound suitable for use in the forming the gaseous mixture is titanium isopropoxide Ti[OCH(CH ₃ ) ₂ ]4. Another example of a titanium alkoxide compound suitable for use in the forming the gaseous mixture is titanium ethoxide Ti(OEt) ₄ . However, the invention is not limited to titanium isopropoxide and titanium ethoxide as other organic titanium- containing compounds may be suitable for use in practicing the CVD process.

In an embodiment, the silicon-containing compound is a silane compound. Preferably, the silane compound is monosilane (SiH ₄ ). However, other silane compounds are suitable for use in practicing the CVD process. For example, disilane (Si ₂ H ₆ ) is a suitable silane compound for use in the CVD process.

Silane compounds may be pyrophoric and when oxygen-containing compounds alone are mixed with a pyrophoric silane compound, silica is produced, but it is produced at unacceptably high rates, resulting in an explosive reaction. To prevent such an explosive reaction, it is known in the art to utilize a radical scavenger. The presence of the radical scavenger allows the silane compound to be mixed with oxygen-containing compounds without undergoing ignition and premature reaction at the operating temperatures of the process. Advantageously, such a radical scavenger is not required by the CVD process. Thus, the cost and complexity to deposit the silicon oxide portion of the mixed metal oxide coating is reduced in the CVD process.

As noted above, the gaseous mixture comprises an oxygen-containing compound.

Preferably, the oxygen-containing compound is an oxygen-containing organic compound such as, for example, a carbonyl compound. Preferably, the carbonyl compound is an ester. More preferably, the carbonyl compound is an ester having an alkyl group with a β hydrogen. Alkyl groups with a β hydrogen containing two to ten carbon atoms are preferred. Preferably, the ester is ethyl acetate (EtoAc). However, in other embodiments, the ester is one of ethyl formate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate or t-butyl acetate.

It may be preferred to provide and maintain a ratio of the oxygen-containing compound to the titanium-containing compound in the gaseous mixture. In embodiments where the titanium-containing compound is titanium tetrachloride and the oxygen-containing compound is ethyl acetate, the ratio of ethyl acetate to titanium tetrachloride in the gaseous mixture is from 1 :1 to 5:1 . Preferably, the ratio of ethyl acetate to titanium tetrachloride in the gaseous mixture is from 1 .5:1 to 3:1 . More preferably, the ratio of ethyl acetate to titanium tetrachloride in the gaseous mixture is about 2:1 to 2.5:1 .

The precursor compounds are mixed to form the gaseous mixture. The precursor compounds are mixed and maintained at a temperature to avoid premature reaction. Those skilled in the art would appreciate that, when premature reaction does occur, undesirable powder may form in the coating apparatus or on the glass substrate. In the embodiments described herein, the CVD process can be operated for an extended period of time without the formation of undesirable powder which further reduces the cost and complexity to produce the mixed metal oxide coating.

The gaseous mixture may also comprise one or more inert gases utilized as carrier or diluent gas. Suitable inert gases include nitrogen (N ₂ ), helium (He) and mixtures thereof. Thus, the CVD process may comprise providing a source of the one or more inert gases from which separate supply lines may extend.

Preferably, the gaseous mixture is delivered to a coating apparatus. In certain embodiments, the gaseous mixture is fed through a coating apparatus prior to forming the mixed metal oxide coating and discharged from the coating apparatus utilizing one or more gas distributor beams. Descriptions of coating apparatuses suitable for being utilized in the CVD process can be found in published U.S. patent application no. 2012/0240627 and U.S. patent no. 4,922,853, the entire disclosures of which are hereby incorporated by reference.

Preferably, the gaseous mixture is formed prior to being fed through the coating apparatus. For example, the precursor compounds may be mixed in a feed line connected to an inlet of the coating apparatus. In other embodiments, the gaseous mixture may be formed within the coating apparatus. The gaseous mixture exits the coating apparatus and is directed toward and along the glass substrate. Utilizing a coating apparatus aids in directing the gaseous mixture toward and along the glass substrate. Preferably, the gaseous mixture is directed toward and along the glass substrate in a laminar flow.

Preferably, the coating apparatus extends transversely across the glass substrate and is provided at a predetermined distance thereabove. The coating apparatus is preferably located at a predetermined location. When the CVD process is utilized in conjunction with the float glass manufacturing process, the coating apparatus is preferably provided within the float bath section thereof. However, the coating apparatus may be provided in the annealing lehr or in the gap between the float bath and the annealing lehr.

The gaseous mixture reacts at or near the deposition surface of the glass substrate to form the mixed metal oxide coating thereover. The CVD process results in the deposition of a high quality coating on the glass substrate. In particular, the mixed metal oxide coating formed using the CVD process exhibits excellent coating thickness uniformity. In an embodiment, the mixed metal oxide coating is a pyrolytic coating.

By providing a mixed metal oxide coating which comprises titanium oxide and silicon oxide, the coating has a refractive index which is lower than the refractive index of a coating containing only titanium oxide. Providing the mixed metal oxide coating with a refractive index as described allows the coating to be utilized as a color suppression interlayer when the coating is used in, for example, combination with other coating layers or a particular application like an architectural glazing. The mixed metal oxide coating has a refractive index of 2.2 or less. Preferably, the mixed metal oxide coating has a refractive index of 2.15 or less. More preferably, the mixed metal oxide coating has a refractive index of 2.0 or less.

In certain embodiments, the refractive index can be selected by providing a desired ratio of silicon oxide to titanium oxide in the mixed metal oxide coating. In such embodiments, the refractive index of the mixed metal oxide coating may be 1 .5 to 2.2. Preferably, these embodiments, the refractive index of the mixed metal oxide coating is 1.6 to 2.1 . More preferably, the mixed metal oxide coating has a refractive index from 1 .85 to 2.1 .

In another aspect the present invention provides a coated glass article comprising a glass substrate and a mixed metal oxide coating formed over the glass substrate, the mixed metal oxide coating comprising titanium oxide and silicon oxide, wherein the mixed metal oxide coating is more than 50% titanium oxide and has a refractive index of 2.2 or less.

Preferably the mixed metal oxide coating is comprised of 2 to 49% silicon oxide. More preferably the mixed metal oxide coating is comprised of 4 to 35% silicon oxide.

Preferably the mixed metal oxide coating has a refractive index of 1 .5 to 2.2. More preferably the mixed metal oxide coating has a refractive index of 1 .6 to 2.1 . Even more preferably the mixed metal oxide coating has a refractive index of 1 .85 to 2.1 .

Preferably the mixed metal oxide coating is formed directly on the glass substrate.

Preferably the mixed metal oxide exhibits photoactivity.

Preferably the photoactivity of the mixed metal oxide coating is 500 nmol/(cm ² xhr) or more. Preferably the mixed metal oxide coating is a pyrolytic coating.

As discussed above and as shown in Figs 2-4, in certain embodiments, the mixed metal oxide coating 1 is formed directly on the glass substrate 2. In these embodiments, the glass substrate 2 is uncoated at the time of depositing the mixed metal oxide coating 1 . Thus, there are no other coating layers that separate the mixed metal oxide coating 1 from the deposition surface 3 of the glass substrate 2. In other embodiments, like the one illustrated in FIG. 5, the mixed metal oxide coating 1 may be formed over one or more previously deposited coating layers 4, 5. The previously deposited coating layer(s) may be formed in conjunction with the float glass manufacturing process or as part of another manufacturing process and may be formed by pyrolysis or by another coating deposition process, and/or by utilizing one or more additional coating apparatuses. Additionally, as illustrated in Figs 2-3, the CVD process described herein may be utilized in combination with one or more additional coating layers 7, 7A, 7B formed over the mixed metal oxide coating 1 to achieve a desired coating stack. The additional coating layer(s) 7, 7A, 7B may be formed in conjunction with the float glass manufacturing process shortly after forming the mixed metal oxide coating 1 or as part of another manufacturing process. Also, these additional coating layers may be formed by pyrolysis or by another coating deposition process, and/or by utilizing one or more additional coating apparatuses. As discussed, above, the CVD process may be carried out in conjunction with the manufacture of the glass substrate in the well-known float glass manufacturing process. The float glass manufacturing process is typically carried out utilizing a float glass installation such as the installation 10 depicted in the FIG. 1 . However, it should be understood that the float glass installation 10 described herein is only illustrative of such installations.

As illustrated in the FIG. 1 , the float glass installation 10 may comprise a canal section 20 along which molten glass 19 is delivered from a melting furnace, to a float bath section 1 1 wherein the glass substrate is formed. In this embodiment, the glass substrate will be referred to as a glass ribbon 8. The glass ribbon 8 is a preferable substrate on which the mixed metal oxide coating is deposited. However, it should be appreciated that the glass substrate is not limited to being a glass ribbon.

The glass ribbon 8 advances from the bath section 1 1 through an adjacent annealing lehr 12 and a cooling section 13. The float bath section 1 1 includes: a bottom section 14 within which a bath of molten tin 15 is contained, a roof 16, opposite side walls (not depicted) and end walls 17. The roof 16, side walls and end walls 17 together define an enclosure 18 in which a non-oxidizing atmosphere is maintained to prevent oxidation of the molten tin 15.

In operation, the molten glass 19 flows along the canal 20 beneath a regulating tweel 21 and downwardly onto the surface of the tin bath 15 in controlled amounts. On the molten tin surface, the molten glass 19 spreads laterally under the influence of gravity and surface tension, as well as certain mechanical influences, and it is advanced across the tin bath 15 to form the glass ribbon 8. The glass ribbon 8 is removed from the bath section 1 1 over lift out rolls 22 and is thereafter conveyed through the annealing lehr 12 and the cooling section 13 on aligned rolls. The deposition of the mixed metal oxide coating preferably takes place in the float bath section 11 , although it may be possible for deposition to take place further along the glass production line, for example, in the gap 28 between the float bath 1 1 and the annealing lehr 12, or in the annealing lehr 12. Also, as illustrated in the FIG. 1 , the coating apparatus 9 is shown within the float bath section 11 . The mixed metal oxide coating may be formed utilizing one coating apparatus 9 or a plurality of coating apparatuses.

A suitable non-oxidizing atmosphere, generally nitrogen or a mixture of nitrogen and hydrogen in which nitrogen predominates, is maintained in the float bath section 11 to prevent oxidation of the molten tin 15 comprising the float bath. The glass ribbon is surrounded by float bath atmosphere. The atmosphere gas is admitted through conduits 23 operably coupled to a distribution manifold 24. The non-oxidizing gas is introduced at a rate sufficient to compensate for normal losses and maintain a slight positive pressure, on the order of between about 0.001 and about 0.01 atmosphere above ambient atmospheric pressure, so as to prevent infiltration of outside atmosphere. For purposes of the describing the invention, the above-noted pressure range is considered to constitute normal atmospheric pressure. The mixed metal oxide coating is preferably formed at essentially atmospheric pressure. Thus, the pressure of the float bath section 1 1 , annealing lehr 12, and/or in the gap 28 between the float bath 1 1 and the annealing lehr 12 may be essentially atmospheric pressure.

Heat for maintaining the desired temperature regime in the float bath section 11 and the enclosure 18 is provided by radiant heaters 25 within the enclosure 18. The atmosphere within the lehr 12 is typically atmospheric air, as the cooling section 13 is not enclosed and the glass ribbon 8 is therefore open to the ambient atmosphere. The glass ribbon 8 is subsequently allowed to cool to ambient temperature. To cool the glass ribbon 8, ambient air may be directed against the glass ribbon 8 as by fans 26 in the cooling section 13. Heaters (not depicted) may also be provided within the annealing lehr 12 for causing the temperature of the glass ribbon 8 to be gradually reduced in accordance with a predetermined regime as it is conveyed therethrough.

EXAMPLES

The following examples are presented solely for the purpose of further illustrating and disclosing the embodiments of the CVD process.

Examples of the CVD process within the scope of the invention are described below and illustrated in TABLE 1 . In TABLE 1 , the coated glass articles within the scope of the invention are Ex 1 - Ex 4. A comparative example, not considered to be a part of the invention, is also described below and illustrated in TABLE 1 . In TABLE 1 , the comparative example is designated as C1.

A soda-lime-silica glass substrate was utilized in examples Ex 1 - Ex 4 and C1 . The glass substrate utilized in each of Ex 1 - Ex 4 and C1 was moving and formed in conjunction with the float glass manufacturing process. The deposition surface of the glass substrate was at essentially atmospheric pressure when the coatings were deposited.

For Ex 1 - Ex 4 and C1 , a silica coating was deposited on the glass substrate prior to forming the coatings thereover. The resulting coated glass articles of Ex 1 - Ex 4 are of a glass/silica/mixed metal oxide arrangement. The resulting coated glass article of C1 is of a glass/silica/titanium oxide arrangement.

A gaseous mixture comprising certain precursor compounds was formed for each of Ex 1 - Ex 4 and C1 . For Ex -1 - Ex 4, the gaseous mixtures comprised titanium tetrachloride, monosilane, and ethyl acetate. For C1 , the gaseous mixture comprised titanium tetrachloride and ethyl acetate. The flow rates for the titanium tetrachloride and monosilane are as listed in TABLE 1 . The gaseous mixtures utilized for Ex 1 - Ex 4 and C1 also comprised inert gases. The line speed for Ex 1 - Ex 4 and C1 , i.e. the speed of the glass substrate moving beneath the coating apparatus from which the gaseous precursor compounds were delivered, was 10.19 m/min.

The ratio of titanium oxide to silicon oxide in each coating was determined using an XPS technique and is reported in TABLE 1 . Also, the form of the titanium dioxide in each coating is reported in TABLE 1 . The thickness of each coating deposited according to Ex 1 - Ex 4 and C1 is reported in TABLE 1 . The coating thicknesses reported in TABLE 1 were determined using a scanning electron microscope (SEM) and are reported in nanometers (nm). Also, the dynamic deposition rate (DDR) of each coating is reported in TABLE 1 . It should be appreciated that DDR refers to the thickness of the coating multiplied by the line speed in meters per minute (m/min). The DDR is useful for comparing coating deposition rates at different line speeds. Additionally, the deposition rate of each coating is reported in TABLE 1 . The refractive index of each coating at 550 nanometers (nm) deposited according to Ex 1 - Ex 4 and C1 is also listed in Table 1 . The refractive indices were calculated by optical modeling. Finally, the photoactivity of the mixed metal oxide coatings of Ex 1 - Ex 4 and the titanium oxide coating of C1 are listed in TABLE 1 . The photoactivity of the mixed metal oxide coatings of Ex 1 - Ex 4 and the titanium oxide coating of C1 were measured utilizing the chemical methylene blue and after exposing the coatings to ultraviolet radiation.

TABLE 1

As illustrated by Ex 1 - Ex 4, when a silicon-containing compound is utilized in a gaseous mixture which also comprises a titanium-containing compound such as titanium tetrachloride and an oxygen-containing compound such as ethyl acetate, a mixed metal oxide coating comprising titanium oxide and silicon oxide can be deposited on a glass substrate. As illustrated by Ex 1 - Ex 4, utilizing the CVD process, the mixed metal oxide coating can be formed at a deposition rate of more than 5.0 nm/sec. In fact, the mixed metal oxide coatings of Ex 1 - Ex 4 were all formed at a deposition rate of about 10 nm/sec or more. Also, the mixed metal oxide coatings of Ex 1 - Ex 4 were all formed at a DDR of more than 225 nm x m/min.

Additionally, as shown in TABLE 1 , the mixed metal oxide coatings of Ex 1 - Ex 4 have refractive indices which are lower than the refractive index of the titanium oxide coating of C1 .

However, the mixed metal oxide coatings of Ex 1 - Ex 4 all exhibited refractive indices of more than 1 .85. In fact, the mixed metal oxide coatings of Ex 1 - Ex 4 all exhibited refractive indices of 1 .98 or more.

Furthermore, the mixed metal oxide coatings of Ex 1 - Ex 4 exhibited photoactivity.

Advantageously, the photoactivities of the mixed metal oxide coatings of Ex 1 - Ex 4 were all greater than 500 nmol/(cm ² xhr). More advantageously, the mixed metal oxide coating of Ex 1 exhibited a photoactivity of more than 1 ,000 nmol/(cm ² xhr).

The foregoing description is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and processes shown and described herein. Accordingly, all suitable modifications and equivalents may be considered as falling within the scope of the invention.