Quasi-binary phase diagram of Nd 4Ba 2Cu 2O 10Ba 3Cu 5O 8 system

Abstract

Nd 1Ba 2Cu 3O 7− 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 Nd 4Ba 2Cu 2O 10 and 3BaCuO 2 + 2CuO(Ba 3Cu 5O 8) has been constructed.