Synthesis and structure of new Am ? 1Bi2BmO3m + 3 (m = 3) phases

Six new polycrystalline bismuth-containing layered perovskite-like oxides described by the general formula A _m − 1Bi₂B _m O_{3m + 3} (m = 3) were synthesized by high-temperature solid-state reactions. The unit-cell parameters of these compounds were determined as a = 5.438(9) Å, b = 5.462(7) Å, and c = 33.08(6) Å for Bi₄Ti₂Nb_0.5Fe_0.5O₁₂; a = 5.408(6) Å, b = 5.425(9) Å, and c = 32.85(6) Å for Ca_0.5Bi_3.5Ti_2.75W_0.25O₁₂; a = 5.457(0) Å, b = 5.482(2) Å, and c = 32.75(2) Å for NaCaBi₂Nb₃O₁₂; a = b = 3.826(2) Å and c = 32.82(6) Å for Ca_0.25Th_0.25Bi_3.5Ti₃O₁₂; a = b = 3.816(2) Å and c = 32.81(5) Å for Nd_0.5Gd_0.5Bi₃Ti₃O₁₂; and a = b = 3.826(4) Å and c = 32.95(8) Å for Th_0.5Bi_3.5Ti_2.5Ga_0.5O₁₂. The compositions of these compounds are based on the composition of the basic Bi-containing layered perovskite-like Bi₄Ti₃O₁₂ oxide in which Bi^III and Ti^IV atoms are partially or completely replaced with other atoms. The experimental and calculated interplanar spacings determined from X-ray diffraction patterns and the reliability factors of their indexing are reported. __________ Translated from Kristallografiya, Vol. 48, No. 3, 2003, pp. 450–457. Original Russian Text Copyright ? 2003 by Geguzina, Shuvayev, Vlasenko, Shuvayeva, Shilkina. This study was presented at the symposium “Order, Disorder, and Properties of Oxides” (ODPO), Sochi, Russia, 2002.