123 Phases of composition CaBa2Cu2WO8 with substitutions of sodium and potassium for calcium and barium

Tetragonal (123) phases of compositions Ca_0.7Na_0.3Ba₂Cu₂WO₈, CaBa_1.7Na_0.3Cu₂WO₈, and CaBa_1.7K_0.3Cu₂WO₈, where tungsten occurs in Cu(1) positions and Cu³⁺ is in Cu(2) positions, were prepared from CaWO₄, BaCuO₂, and sodium and potassium nitrates at 1073 K in an oxygen flow. These phases constitute at least 90% of the samples; their unit call parameters are as follows: a = b = 0.4177(3) nm, c = 1.2561(8) nm; a = b = 0.4182(3) nm, c = 1.2564(8) nm; and a = b = 0.4194(3) nm, c = 1.2603(8) nm, respectively. Their X-ray diffraction patterns feature peaks that indicate a superstructure with all three unit cell parameters being doubled. The samples have weak conductive properties (room-temperature electrical conductivity ranges between 10^?6 and 10^?7 Ohm^?1 cm^?1). Conductivity versus temperature curves are indicative of the semiconductor character of the samples. Superconducting transitions do not occur up to 65 K.