X-ray diffuse scattering from single crystal LiNbO3and LiTaO3as a function of temperature between 20–750°C

Abstract
Some changes observed in single crystal LiNbO3 and LITaO3, when the temperature was raised from 20 to 750°C are compared using well-known results in infrared spectroscopy, Raman spectra and data which were obtained using the method of diffuse scattering. The observed x-ray diffraction effects in single crystal LiNbO3 when heated are compared with those which are revealed in stoichiometry deviation (the ratio Li/Nb is changed from 0.895 to 1.00) and the influence of the radiation (∼4×1020 nsm−2; E ≥ 0.5 meV, T Irrad, ≃ 150°C). The results of space distribution of intensity near some reciprocal lattice nodes in stoichiometric crystal LiNbO3 and LiTaO3 at 20°C which are obtained with the help of an autodifractometer “Syntex P1” (Mo Ka) are also given.