OXYGEN-DEFICIENT AND ORDERED PEROVSKITE-TYPE SOLID-SOLUTION SYSTEM BA1+XBI1-XOY(0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.5, 3.00-GREATER-THAN-OR-EQUAL-TO-Y-GREATER-THAN-OR-EQUAL-TO-2.75)

A new oxygen-deficient and ordered perovskite-type solid-solution system Ba1+xBi1-xOy(0 ≦ x ≦ 0.5, 3.00 ≧ y ≧ 2.75) was synthesized, with the estimated ionic configuration Ba(Ba2+xBi3+3.5-1.5x-yBi5+-3+0.5x+y)(Bi5+0.5)Oy. The lattice parameters and mean valence of bismuth in the samples annealed in one atmosphere of oxygen at 773 K were determined by the powder X-ray diffraction method and iodometric titration method, respectively. Samples with the compositions 0 ≦ x ≦ 0.05, 0.10 ≦ x ≦ 0.15, 0.20 ≦ x ≦ 0.425, 0.45 ≦ x ≦ 0.475, and 0.475 < x ≦ 0.50 were found to be monoclinic, rhombohedral, cubic, tetragonal, and cubic, respectively. Oxygen deficiency was observed in the entire range of the composition; the ordering of the oxygen vacancies was confirmed in the range X ≧ 0.45. © 1990.