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Title: Tetrastrontium-digalliumoxide (Sr{sub 4}Ga{sub 2}O{sub 7})-synthesis and crystal structure of a mixed anion strontium gallate related to perovskite

Crystal growth experiments yielded single crystals of Sr{sub 4}Ga{sub 2}O{sub 7}. The title compound is monoclinic, space group P1c1, a=13.0822(7)A, b=15.7967(6)A, c=15.8586(8)A, {beta}=90.643(6){sup o}, V=3277.1(3)A{sup 3}, Z=16 (R1=0.041 for 7155 observed reflections and 660 parameters). The crystals showed twinning by pseudo-merohedry. Furthermore, the diffraction data exhibited the typical features of a superstructure. Sr{sub 4}Ga{sub 2}O{sub 7} can be classified as a mixed anion gallate comprising insular [GaO{sub 4}]-groups and [Ga{sub 3}O{sub 10}]-trimers. Both anion groups are located in layers perpendicular to [100]. 32 symmetrically independent Sr-cations crosslink between the tetrahedral anion groups. Alternatively, the compound can be described as a 3x4x4 superstructure of ABO{sub 3} perovskite, with 22.2% vacancies in the oxygen sublattice. The relationship with perovskite can be expressed in the following crystal chemical formula: Sr(Ga{sub 2/3}Sr{sub 1/3})(O{sub 7/9}-bar {sub 2/9}){sub 3}. A discussion of the structure in the context with other similar defect perovskites in presented.
Authors:
 [1] ;  [2] ;  [2] ;  [3]
  1. Institut fuer Mineralogie und Petrographie, Leopold-Franzens-Universitaet Innsbruck, Innrain 52, A-6020 Innsbruck (Austria). E-mail: volker.kahlenberg@uibk.ac.at
  2. Institut fuer Mineralogie und Petrographie, Leopold-Franzens-Universitaet Innsbruck, Innrain 52, A-6020 Innsbruck (Austria)
  3. (Russian Federation)
Publication Date:
OSTI Identifier:
20725917
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 178; Journal Issue: 5; Other Information: DOI: 10.1016/j.jssc.2005.02.009; PII: S0022-4596(05)00061-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANIONS; CRYSTAL GROWTH; DIFFRACTION; GALLIUM COMPOUNDS; LAYERS; MONOCLINIC LATTICES; MONOCRYSTALS; OXIDES; PEROVSKITE; SPACE GROUPS; STRONTIUM COMPOUNDS; SYNTHESIS; TWINNING; VACANCIES