PHASE-DIAGRAM STUDIES AND CRYSTAL-GROWTH OF PRBA2CU3O7-Y

In this work a physico-chemical investigation of the crystal growth of PrBa2Cu3O7-y (PrBCO) has been carried out with the aid of improved thermogravimetric analysis (ITGA) and differential thermal analysis (DTA). The phase diagram of CuO-BaCuO2. has been established by ITGA, and the eutectic composition, found to be 0.72CuO+0.28BaO, was chosen as the flux for the crystal growth. Studies of the decomposition of (Y1-xPrx)BCO with various doping concentrations, and of the pseudo-binary phase diagram of PrBCO-flux, were made by DTA. This information was used to grow and separate crystals of PrBCO from the flux above the eutectic temperature, and single crystals of PrBCO up to 10X5X0.8 mm3 were obtained by spontaneous nucleation. Polarised neutron diffraction experiments have been performed on these crystals and indicate some substitution of Pr on the Ba site in the as-grown samples.