Thermal study of superconducting Ba2Cu3RO7-x (R = Y, Eu. Gd, Ho)

Abstract Polycrystalline black coloured samples of Ba 2 Cu 3 RO 7-x (R = Y, Eu, Gd, Ho) have been prepared from mixtures of BaO 2 , CuO and R 2 O 3 , which were ground, pelletized and heated in air at 975 °C for 3 days, and slowly cooled in an oxygen-enriched air atmosphere. The resulting products are pure orthorhombic phases, S.G. Pmmm No. 47, Z = 1. Structural data are given. The TG studies carried out in both hydrogen and nitrogen dynamic atmospheres, have allowed to establish the oxygen content of the samples, which compare with those determined from populations of the oxygen positions after refining the X-ray diffraction intensities.