Phase equilibria in the ternary reciprocal system Li, Ba // BO2, F and growth of bulk β-BaB2O4 crystals

In order to find the optimum solvent for the growth of nonlinear optical β-BaB2O4 crystals, the phase relationships in the ternary reciprocal system Li, Ba // BO2, F have been studied using solid state synthesis, differential thermal analysis and X-ray powder diffraction. Isothermal and polythermal sections of the system Li, Ba // BO2, F are reported. In the studied system, the following compounds are formed: LiBa2B5O10 (melts by peritectic reaction at 930°C, i.e. 1203 K) and LiBaF3 (melts incongruently at 850°C, i.e. 1123 K). Visual polythermal analysis of seeding and growth of β-BaB2O4 crystals in this system was carried out. The primary crystallization field of β-BaB2O4 was defined. Using the top-seeded pulling technique, a β-BaB2O4 crystal of 93 mm in diameter, 34 mm in height and 520 g in weight has been grown.

BEHAVIOUR AND NATURE OF DISINTEGRATION OF SLID SOLUTIONS BASED ON SODIUM AND CALCIUM SULPHATES IN TERNARY SULPHATE SYSTEMS

Information on phase formation in complex physical-chemical systems is the basis for the synthesis of new phases and thus informational-logical basis for the developing of new polyfunctional materials. For the first time set of sulfate-containing ternary systems was studied using a complex of methods for physical and chemical analysis, such as differential thermal analysis (DTA), visual-polythermal analysis (VPA). The nature of solid solutions based on Na2SO4–CaSO4 was identified; the values of force fields were calculated by Goldschmidt’s formula. The influence of the third component (М2SO4 (М-Li,K,Rb,Cs,Tl(I)) on the behavior and disintegration of these solid solutions was determined.