The influence of the ionic size of the lanthanides R on melting relations of Ba2RCu3O6+x, where R=Y, Eu and Nd, was studied and compared with that of a high Tc superconductor mixed-lanthanide phase Ba2(Y.75Eu.125Nd 125)Cu3O6+xThese materials have been characterized by a variety of methods including differential thermogravimetric analysis (DTA), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction. Single phase samples of Ba2(Y.75Eu.125Nd.125)Cu3O6+x were annealed at 1004, 1040, 1052, 1060, 1078, 1107 and 1160°C and quenched into a helium gas container cooled by liquid nitrogen. The SEM micrographs of these samples showed the progressive chnages in features of the microstructures from sintering and grain growth through melting and then recrystallization from the melt. The addition of the SEM technique in conjunction with X-ray diffraction has been helpful in the study of phase equilibria in this system.
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Certain commercial materials and equipment are identified in this article to specify the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology.
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Wong-Ng, W., Cook, L.P., Hill, M.D. et al. Crystal Chemistry and Phase Equilibrium Studies of the Bao(baco3)-r2o3-cuo Systems. V. Melting Relations in ba2(y,nd,eu)cu3o6+x . MRS Online Proceedings Library 169, 81–86 (1989). https://doi.org/10.1557/PROC-169-81