INFLUENCE OF MGO DOPING ON THE STRUCTURE OF MONOCRYSTALLINE LINBO3

Conditions for the growth of LiNbO3:MgO single crystals by the Czochra lski method were optimized. An upper limit of the molar MgO concentrat ion in the melt for obtaining limpid, optically homogeneous crystals w as determined. The Curie temperature was measured on precisely defined samples and so real MgO contents in the single crystal phase, distrib ution coefficients and longitudinal concentration profiles could be de termined using this calibration curve. X-ray diffraction and optical a bsorption in the near infra-red and in the ultra-violet and visible re gions were also studied on LiNbO3:MgO single crystals. Lattice constan ts and positions of the OH- absorption band and of the short-wave abso rption edge were determined on the basis of described measurements. De pendences of all the above-mentioned properties on the molar MgO conce ntration were found out. The simple model of microscopic mechanisms fo r explaining these experimental data was proposed.