Determination of the composition of lithium tantalate crystals by zero-birefringence measurements

Abstract

We present an approach to determine the exact composition of lithium tantalate (LiTaO3) crystals by measuring the temperature where the birefringence disappears. Various samples with compositions ranging from the congruently melting to the stoichiometric one have been prepared by vapor transport equilibration treatments and are investigated. The sensitivity is as high as 1.5 °C/0.01 mol % Li2O. The relative accuracy is better than 0.01 mol %, while the absolute accuracy is limited by the calibration.