SOLID-SOLUTIONS IN THE BA2Y1-XCUXWO6-Y SYSTEM

The crystalline structure of the Ba2Y(1-x)Cu(x)WO6-y system was obtained from x-ray diffraction measurements as a function of copper concentration. Five different x regions are observed, four of which correspond to solid solutions and lie at x less-than-or-equal-to 0.75. The crystalline structure of the phases at these copper concentrations has cubic symmetry with lattice parameters between 0.8382 and 0.8275 nm. At 0.75 < x less-than-or-equal-to 1.0 the samples are a mixture of two phases. In this study we have identified the existence of only two stoichiometric compounds: Ba8Y3CuW4O24 with a cubic crystalline structure with space group Pm3m and lattice parameter of 0.8350(1) nm, and Ba2CuWO6 with a crystalline tetragonal structure and space group I4/mmm and lattice parameters a = 0.5566(1) nm and c = 0.8634(1) nm. The crystalline structure at all copper concentrations is based in the ordered perovskite structure. The samples show electrical insulator behavior.