Distorted kossel diffraction of LiNbO3 in the vicinity of 75°C

Abstract

Some abnormal Kossel lines of pure LiNbO3 crystal have been observed in the vicinity of 75°C and in Ti-diffused one at wide temperature range. Reasonable explanation is that the diffraction plane inclines locally from its normal position at that temperature. A computer simulation has been made and shows an agreement with the calculations. The change of elastic constant or heat expansion coefficient etc. may be the cause of the deformation of the pure crystal near 75°C.