Quasi-binary phase diagram of Nd4Ba2Cu2O10-Ba3Cu5O8 system

Nd1Ba2Cu3O7-y (Nd123) melt processed in a reduced oxygen atmosphere exhibits good superconducting characteristics including high T-c and high J(c). Hence, its single crystal is required for evaluation of fundamental superconducting properties as well as for future devices of high temperature superconductive oxides. Information of the phase diagram especially in the range of obtaining Nd123 single crystals from solution is indispensable to fabricate Nd123 single crystals by the Top-Seeded Solution Growth (TSSG), which has not been fully investigated yet. In this work, the temperature dependence of Nd solubility in the Ba-Cu-O solution with a Ba to Cu ratio of 3 to 5 was investigated by analyzing the composition of the solution stuck to the thermally equilibrated MgO single crystal which was dipped into the equilibrated solution at different temperatures. Transformation temperatures including the peritectic temperature and stable phases were measured by X-ray diffraction (XRD) by quenching samples held isothermally around the transformation temperature estimated in advance by differential thermal analysis (TG-DTA). From these experiments the phase diagram of quasi-binary system between Nd4Ba2Cu2O10 and 3BaCuO(2) + 2CuO(Ba3Cu5O8) has been constructed.