Nonstoichiometric composition of lithium niobate crystal

Abstract

The disturbance of stoichiometry of lithium niobate crystals, which are grown by the Czochralski technique, is considered in this paper. According to the authors point of view the main reason of the disturbance of stoichiometry is the deficit of oxygen of pentaoxide of niobium Nb²O_5-x, which is used to make the initial melt. On the basis of comparison of the calculated X-ray density with the experimental data, a model was suggested, which differs from the model by Abrahams. According to this model niobium occupies the lithium positions when forming oxygen vacancies. However, it is necessary to apply a correction in the calculations for distribution of Li₂O between the crystal and the initial melt.