Study of the bipyramidal site in magnetoplumbite-like compounds, SrM12O19 (M = Al, Fe, Ga)

doi:10.1016/0022-4596(90)90081-8

Journal of Solid State Chemistry

Volume 87, Issue 1, July 1990, Pages 186-194

https://doi.org/10.1016/0022-4596(90)90081-8 Get rights and content

Abstract

Structures of magnetoplumbite-type crystals SrM₁₂O₁₉ (M = Al, Fe, Ga) have been refined by the single-crystal X-ray diffraction method. The space group is P6₃/mmc with Z = 2. The cell dimensions are a = 5.5666(2) and c = 22.0018(8) Å for SrAl₁₂O₁₉, a = 5.8836(1) and c = 23.0376(9)Å for SrFe₁₂O₁₉, and a = 5.7929(1) and c = 22.8123(7) Å for SrGa₁₂O₁₉ at 22°C. Four structural models were tested with respect to the states of M atoms at trigonal bipyramidal sites: central atom and split atom models with and without anharmonic thermal vibrations. The simple split atom model gave lower R_w values than the central atom model with anharmonic thermal vibrations for SrAl₁₂O₁₉ and SrGa₁₂O₁₉, whereas it gave an R_w value approximately equal to that given by the central atom model with anharmonic vibration for SrFe₁₂O₁₉. The present study suggested that the potential around the M atom with trigonal bipyramidal coordination has double minima in all the magnetoplumbite-type crystals at lower temperatures.

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Regular articleStudy of the bipyramidal site in magnetoplumbite-like compounds, SrM12O19 (M = Al, Fe, Ga)

Abstract

J. Solid State Chem.

J. Solid State Chem.

J. Solid State Chem.

J. Solid State Chem.

J. Solid State Chem.

J. Solid State Chem.

J. Solid State Chem.

J. Phys. Chem. Solids

Ark. Kemí Mineral. Geol. Ser. A

Regular article
Study of the bipyramidal site in magnetoplumbite-like compounds, SrM₁₂O₁₉ (M = Al, Fe, Ga)