To provide a method for producing a high purity calcium fluoride usable as an optical member in the range of a vacuum ultraviolet wavelength and having an extremely small amount of metal impurity content, and also provide a method for producing the intermediate thereof, and a high purity calcium fluoride.
The production method comprises a process for adding an alkali to a calcium compound to produce calcium hydroxide in the range of pH 12 to 13.5 (process 1), a process for adding an acid to calcium hydroxide produced via the process 1 to adjust the value of pH 1 to 7 and then adding oxalic acid to the mixture to produce calcium oxalate (process 2) and a process for adding hydrogen fluoride to calcium oxalate produced via the process 2 to produce calcium fluoride (process 3).
NAKASAKI SUSUMU
ATOBE HITOSHI
