CRYSTALLIZATION REGIONS OF THE LA2CU2O5 AND LA1-XSRXCUO2.5-DELTA PHASES IN THE LA2O3-SRO-CUO SYSTEM

The La2Cu2O5 and La1-xSrCuO2.5-delta crystallization regions have been investigated in the system La2O3-SrO-CuO at fixed molar ratio La2O3:C uO=1:8 in the range of SrO concentrations from 0.0 to 5.5 mol%. It has been shown that Sr is non-soluble in La2Cu2O5 and the crystallization region of this phase is limited by the SrO concentration in the melt congruent-to 1 mol%. When the SrO concentration in the melt exceeds co ngruent-to 1% mol%, the La1-xSrxCuO2.5-delta phase crystallization tak es place below 1050-degrees-C. The Sr lower solubility limit in La1-xS rxCuO2.5-delta is found to be x congruent-to 0.05 atoms/Fu. This compo und does not exist if the Sr content is lower. The tentative projectio ns of the primary crystallization phase boundaries of CuO, La2Cu2O5, L a1-xSrxCuO2.5-delta and La2-xSrCuO4-delta phases on the La2O3-SrO-CUO composition triangles have been constructed.