METHOD FOR PRODUCING LITHIUM TANTALATE CRYSTAL AND WAFER FORMED FROM THE LITHIUM TANTALATE CRYSTAL

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a lithium tantalate crystal in which the pyroelectric property is suppressed; and to provide a wafer formed from the lithium tantalate crystal.

SOLUTION: The method for producing a lithium tantalate crystal includes: preparing at least a lithium tantalate crystal base material and a reducing agent (Figs.A, C); then immersing the base material into a solution containing a metal halide (Fig.B); and after superposing the reducing agent and the lithium tantalate crystal base material, heat treating the reducing agent and the base material at a temperature equal to or lower than Curie temperature in a reducing atmosphere until a reaction by the heat treatment becomes an equilibrium state (Fig.D). In the method, the electrical conductivity of the lithium tantalate crystal obtained after heat treatment is controlled to be within the range of from 1×10-13to 9.99×10-12Ω-1×cm-1and the distribution in the crystal plane of the electrical conductivity is controlled to be uniform by adjusting the reducing power of the reducing agent being prepared.

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