Phase Equilibria Relations in the Ternary System BaO-SrO-Nb[sub 2]O[sub 5]

Phase equilibria in the binary system and the ‐rich region of the ternary system were investigated by DTA, x‐ray diffraction, strip heater, and Curie temperature measurement techniques. The ternary‐phase fields of three tetragonal‐tungsten‐bronze type structures have been located, Only one of these structures is a ternary compound; it is located along the binary join, extending from 20 to 80 m/o , and melts congruently near 50% . The ternary solubility extends from about 4% excess to about 1% excess . This phase possesses observable orthorhombic distortion in the ‐rich region of the solid solution. The implications of the phase diagram for the crystal growth of these compounds are briefly discussed.