Subsolidus phase relations of the SrO-WO3-CuO system at 800 °C in air

The subsolidus phase relations of the SrO-WO3-CuO system were investigated in air. The samples were equilibrated at 800 degrees C. Under these conditions, eight binary oxides are stable. The pseudo-ternary section contains two ternary oxide phases: the previously described Sr2CuWO6 phase as well as a new phase with Sr8CuW3O18 stoichiometry. The crystal structure of this new compound was solved and refined in the R-3 space group, unit cell parameters a = 5.7202 angstrom and c = 28.873 angstrom. Sr8CuW3O18 has a distorted perovskite type structure, where some of the Sr atoms are positioned at the B sites, and the composition may be given as: Sr-6(S2CuW3)O-18. There are indications of existence of a superstructure or stacking faults related to Cu/Sr ordering. (C) 2011 Elsevier B.V. All rights reserved.