0000000000377099
AUTHOR
C. C. Luhrs
Crystal chemistry and redox behaviour of antimony strontium calcium perovskites
The compound Sr2Sb1.4Ca0.6O6 and their reduced forms Sr2Sb1.4Ca0.6O5.17 and Sr2Sb1.4Ca0.6O4.84 have been prepared and characterized by powder X-ray diffraction, electron diffraction, iodometric analyses and thermogravimetric analysis. The three phases with different oxygen stoichiometries are structurally related to the perovskite and show symmetry distortions from the ideal cubic structure (with cell parameter ap). The crystal structure of Sr2Sb1.4Ca0.6O6 may be refined by the Rietveld method from powder X-ray diffraction data using the space group P21/n, and the cell parameters a=5.776(2), b=5.7837(2), c=8.1718(3) A, β=90.039(3)° with the same structural model than for previously studied …
Crystal structure of Bi_{6}Sr_{8-x}Ca_{3+x}O_{22}(-0.5\leq x\leq1.7)$: a mixed valence bismuth oxide related to perovskite
Abstract: The crystal structure of BiSr8-xCa3+xO22 has been determined by single-crystal X-ray diffraction. This phase is the same as Bi9Sr11Ca5Oy that was previously studied by several authors as a secondary phase in the Bi-Sr-Ca-Cu-O system and coexists in thermodynamic equilibrium with the superconductors Bi2Sr2CuO6 and Bi2Sr2CaCu2O8 It crystallizes in the monoclinic space group P2(1)/c, with cell parameters a 11.037(3) Angstrom, b = 5.971(2) Angstrom, c = 19.703(7) Angstrom, beta = 101.46(3)degrees Z = 2. The structure was solved by direct methods and full-matrix least-squares refinement. It is built up by perovskite-related blocks of composition [Sr8-xBi2Ca3+xO16] that intergrow with d…