METHOD FOR ETCHING OF SINGLE CRYSTALS OF LITHIUM TANTALATE Russian patent published in 1995 - IPC

FIELD: hydrothermal etching. SUBSTANCE: method for etching of single crystals of lithium tantalate consists in treatment of single crystals of lithium tantalate in hydrothermal conditions at temperature of 450-300 C and pressure of not less than 50 atm. Etching solutions are used in form of aqueous solutions of mixture of acid H₃PO₄ or HNO₃ and one of salts MeNO₃, MeF, MeHF₂ where Me is alkali metal, or in aqueous solutions of one of salts MeNO₃, MeF, MeHF₂, or aqueous solution of alkali MeOH and salt MeNO₃.. EFFECT: provision for etching of large single crystals sizing above 2x10x10 mm (crystals do not cracking in etching), excluded use of expensive inactive temperature-stable materials such as platinum, iridium and cut down costs of the process and higher rate of etching.