Synthesis, stoichiometry and structure of the quaternary scandium cuprate Ba3Cu3Sc4O12 and of 334-phase solid solution members Ba3Cu3Sc4 − xInxO12 (0 ≤ x ≤ 4)

Abstract

The quaternary scandium cuprate Ba3Cu3Sc4O12 has been prepared via the high temperature solid state reaction of the respective binary oxides and BaCO3 in air at 950 °C. The cuprate was characterised by powder X-ray diffraction (PXD) and its structure determined for the first time by Rietveld refinement of powder data. Crystallite morphology and metal stoichiometry were examined by SEM/EDAX. Oxygen stoichiometry and thermal behaviour were evaluated by TG/DTA and TPR. Ba3Cu3Sc4O12 crystallises with a tetragonal, perovskite-derived structure in space group I4/mcm (a = 11.9021(6) Å, c = 8.3962(4) Å, V = 1189.41(10) Å3, Z = 4, c/a = 0.71), isostructural with Ba3Cu3In4O12. Ba3Cu3Sc4O12 is paramagnetic at room temperature consistent with Cu(II). In readily substitutes for Sc to form Ba3Cu3Sc4 − xInxO12 334-phases continuously to Ba3Cu3In4O12 (x = 4). Structures of selected members have been determined from PXD data and correlated to the trivalent cation substituent level, x.