Abstract :
Isomorphism of ions in Ca3Ga2Ge4O 14-type structure is considered and criteria of search for new compositions in four-component oxide systems are formulated. The preparation of two new groups of disordered four-component compositions is reported. Ln3Ga3Ge2BeO14, possessing wide range of homogeneity, exist with Ln = La-Eu. Substitution for Be2+ in 2d tetrahedral site shifts Ln:Ga ratio from garnet one 3:5 to 1:1 and decreases garnet structure stability. This enables to introduce smaller, then Nd3+, rare earth ions Sm3+ and Eu3+. Four-component solid solutions are found in binary section A3BxM2 Si4-xO14 of silicate systems AO-BO2 -M2O3-SiO2 (A=Ca, Sr, Ba; B=Ge, Ti, Sn, Zr; M=Ga, Fe). Some Ti-Ga-silicate compositions look promising for melt crystal growth. Principles of crystallization in four-component system are discussed
Keywords :
crystal chemistry; crystal growth from melt; crystal structure; crystallisation; gallium compounds; isomorphism; lanthanum compounds; phase diagrams; piezoelectric materials; stoichiometry; Ca3Ga2Ge4O14; Czochralski growth; binary sections; crystallization; disordered compositions; four-component oxide systems; garnet structure stability; homogeneity field; isomorphism of ions; langasite family compositions; melt crystal growth; piezoelectric parameters; stoichiometry; tetrahedral site; Crystallization; Garnets; Milling machines; Niobium; Solids; Stability; Strontium; Temperature sensors; Tin; Zirconium;
