Lithium tantalate substrate and process for its manufacture

Abstract

A lithium tantalate substrate obtained by working in the state of a substrate a lithium tantalate crystal grown by the Czochralski method is buried in a mixed powder of Al and Al 2 O 3 , followed by heat treatment carried out at a temperature kept to from 350 to 600° C., to manufacture a lithium tantalate substrate having volume resistivity which has been controlled within the range of from more than 10 8 to less than 10 10 Ωcm. The substrate obtained has no pyroelectricity, and it can be made colored and opaque from a colorless and transparent state and also sufficiently has the properties required as a piezoelectric material.

1 . A lithium tantalate substrate having volume resistivity which has been controlled within the range of from more than 10 8  to less than 10 10  Ωcm. 
   
   
       2 . The lithium tantalate substrate according to  claim 1 , which has a heat history of being subjected to heat treatment at a temperature kept to from 350 to 600° C., in the state of being buried in a mixed powder of Al and Al 2 O 3 . 
   
   
       3 - 4 . (canceled)