PHASE-RELATIONS AND COMPOUNDS IN THE SM2O3-BAO-CUO SYSTEM AT 950-DEGREES-C IN AIR

The subsolidus phase relations of the Sm2O3-BaO-CuO system at 950-degr ees-C in air were investigated. The system can be divided into eight t hree-phase regions and two two-phase regions. There is one ternary com pound Sm2BaCuO5, a solid solution Sm1+xBa2-xCu3Oy, and three binary co mpounds Sm2CuO4, BaCuO2, and Sm2BaO4. Sm2BaO4 was isolated with orthor hombic unit cell, space group Pbna, and lattice constants a = 12.313 a ngstrom, b = 10.535 angstrom and c = 3.564 angstrom. The solid solutio n range of Sm1+xBa2-xCu3Oy was determined from x = 0 to 0.4, and a pha se transition from orthorhombic to tetragonal symmetry occurs at x = 0 .25. With an increase in x, T(c) decreases monotonically from 94 K (on set), and the compounds of Sm1+xBa2-xCu3Oy finally become semiconducti ng.