Manufacture of highly purified metal fluoride, e.g. calcium fluoride for preparing optical items, involves heating a less pure metal fluoride and treating with fluorinating agent

摘要

A highly purified metal fluoride is manufactured by heating a less pure metal fluoride up to a temperature allowing a sufficient mobility of the impurities in the crystal lattice and treating the metal fluoride with fluorination agent. An independent claim is also included for an optical item obtainable from a monocrystal of an alkaline earth metal fluoride manufactured by the inventive process.