The effect of cation size on the structural stability of various oxide materials is discussed based on experimental observations of segregation, phase formation, congruency, and other parameters determining crystal growth conditions. The results indicate that the procedures necessary for optimization of crystal composition include growth of mixed crystals, composition analysis, calculation of segregation coefficients, and estimation of the relationship between the structural stability of the end member compounds forming the mixed crystals.

Keywords: Oxide crystal, garnet, structural stability, cation size, segregation, mixed crystals