Specific features of growth of single crystals of complex oxides with an oxygen deficit

Some methods for estimating the concentration of vacancies in crystals and procedures for decreasing their number are considered by the example of LiNbO3, SrTiO3, YAlO3, and PbWO4 crystals. In LiNbO3 crystals, nonstoichiometry was determined by comparing the density determined via X-ray diffraction with the experimental value. In SrTiO3 and YAlO3 crystals, the vacancy concentration was estimated with methods based on additivity of refractions. The vacancy concentration in the LiNbO3 and PbWO4 crystals was decreased by doping them with elements of lower valence and annealing in air and vacuum. Some specific features of the growth of PbWO4 crystals affecting their quality are discussed. Peculiarities of the formation of lithium niobate, strontium titanate, yttrium orthoaluminate, and lead tungstate crystals are considered.