Subsolidus phase relations of the SrO-RE2O3-CuO systems (REÂ =Â Tm, Lu and Sc)

The subsolidus phase relations of the SrO-RE2O3-CuO (RE = Tm, Lu, Sc) systems were investigated in air. The samples were synthesised at 900 °C. The Sr14−xRExCu24O41−δ solid solution was the only ternary phase formed for RE = Tm and Lu. The solubility limit of Sc in the Sr14Cu24O41−δ phase is extremely low and substitution may take place on the Cu sites rather than on the Sr sites. The three systems comprise 6 three-phase regions and there are 2 two-phase regions in the systems including Tm and Lu. The structure of the SrO-Tm2O3-CuO and SrO-Lu2O3-CuO systems is similar to the one of the SrO-Yb2O3-CuO and SrO-Er2O3-CuO systems. There are however, significant differences in the SrO-Sc2O3-CuO system.