30 KBAR PHASE-EQUILIBRIA OF THE LA2O3-SRO-CUO SYSTEM AT 950-DEGREES-C

Phase equilibria of the La2O3-SrO-CuO system have been determined at 9 50 degrees C at 30 kbar (3 GPa). Stable phases at the apexes of the te rnary phase diagram are CuO, La2O3, and SrO. Stable intermediate phase s are La2CuO4 and La2Cu2O5 in the LaO1.5-CuO binary and Sr2CuO3, SrCuO 2, and Sr14Cu24O41 in the CuO-SrO binary. The La2-xSrxCuO4-delta solid solution is stable for 0.00 less than or equal to x less than or equa l to 1.29, the La2-xSr1+xCu2O6+delta solid solution is stable for 0.03 less than or equal to x less than or equal to 0.20, the La2-xSrxCu2O5 -delta solid solution is stable for 0.00 less than or equal to x less than or equal to 1.08, and the LaxSr14-xCu24O41 solid solution is stab le for 0.00 less than or equal to x less than or equal to 6.15. The 30 kbar phase diagram differs from the 1 atm (0.1 MPa) and 10 kbar (1 GP a) results principally in the absence of La1-xSr2+xCu2O5.5+delta as a stable phase and the extended range of the La2-xSrxCu2O5-delta solid s olution at 30 kbar.