Producing fluorite crystal, comprises performing melting-solidification step by melting mixture of calcium fluoride powder having scavenger, and solidifying melted mixture by cooling to obtain melt-solidified body A

摘要

The method comprises performing a melting-solidification step by melting a mixture of a calcium fluoride powder having a scavenger, solidifying the melted mixture by cooling to obtain a melt-solidified body A, shattering the total amount of the melt-solidified body A in the debris of the melt-solidified body, and melting a mixture obtained by mixing the total amount of debris of melt-solidified body with the scavenger, solidifying the mixture by cooling to obtain a melt-solidified body B, and performing a fragmentation step. The method comprises performing a melting-solidification step by melting a mixture of a calcium fluoride powder having a scavenger, solidifying the melted mixture by cooling to obtain a melt-solidified body A, shattering the total amount of the melt-solidified body A in the debris of the melt-solidified body, and melting a mixture obtained by mixing the total amount of debris of melt-solidified body with the scavenger, solidifying the mixture by cooling to obtain a melt-solidified body B, performing a fragmentation step by shattering the total amount of melt-solidified body B in the melt-solidified debris body, performing a crystal growth step by melting the debris of the melt-solidified body, cooling to grow a crystal and to obtain a fluorite crystal, and performing a heat treatment step by heat treating the fluorite crystal obtained in the crystal growth step, where an amount of the admixed scavengers is 1-4 mol.% based on 100 mol.% of calcium fluoride in the debris of the melt-solidified body resulting by shattering of the total amount of the melt-solidified body A or based on 100 mol.% of the calcium fluoride in the debris of the melt-solidified body resulting by shattering of the total amount of the melt-solidified body B. An independent claim is included for: (1) an intermediate product of fluorite crystal preparation; and (2) a fluorite crystal.