SOLID PHASE RELATIONS AT 950 degree C IN La-Ba-Cu-O.

Subsolidus phase relations in the La//2O//3-BaO-CuO system were studied at 950 degree C. Three previously reported binary compounds exist (La//2CuO//4, BaLa//2O//4, and BaCuO//2) and five previously reported ternary phases occur. Of the seven phases in the diagram, all but BaLa//2O//4, BaCuO//2, and La//4BaCu//5O//1//3// plus // delta were shown to exhibit significant ranges of solubility. The diagram is important in that both greater than 30 K (La//2// minus //xBa//xCuO//4// minus //(//x/////2//,// plus // delta ) and greater than 90 K (La//3// minus //xBa//3// plus //xCu//6O//1//4// plus // delta //, x equals 1) superconductors occur.