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Structural Studies of Bi 2 (Fe x Al 1– x ) 4 O 9 Solid Solutions (0.1 ≤ x ≤ 1.0) Prepared by a Combined Mechanochemical/Thermal Synthesis
Author(s) -
Da Silva Klebson L.,
Šepelák Vladimir,
Paesano Andrea,
Litterst F. Jochen,
Becker KlausDieter
Publication year - 2010
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201000032
Subject(s) - mössbauer spectroscopy , octahedron , rietveld refinement , crystallography , orthorhombic crystal system , paramagnetism , solid solution , materials science , x ray crystallography , valence (chemistry) , chemistry , crystal structure , analytical chemistry (journal) , diffraction , physics , metallurgy , condensed matter physics , organic chemistry , chromatography , optics
Bi 2 (Fe x Al 1– x ) 4 O 9 solid solutions with 0.1 ≤ x ≤ 1.0 prepared by mechanochemical processing of α‐Fe 2 O 3 /Bi 2 O 3 /Al 2 O 3 mixtures and subsequent annealing were investigated by X‐ray diffraction, Mössbauer spectroscopy, and EDX. A Rietveld refinement was made for the whole range of the solid solutions. The structure is orthorhombic with space group Pbam . Mössbauer spectroscopy reveals paramagnetic behavior for Bi 2 (Fe x Al 1– x ) 4 O 9 with 0.1 ≤ x ≤ 1.0 at room temperature and indicates significant distortion of the octahedral iron coordination for aluminum‐rich mixed crystals. The occupancy of octahedrally and tetrahedrally coordinated sites was determined by Mössbauer spectroscopy and Rietveld analysis. For x ≥ 0.5, the Mössbauer measurements as well as the Rietveld refinements show an almost random distribution of aluminum and iron cations over the two non‐equivalent sites, whereas for x < 0.5, a slight preference of iron for the octahedral sites is observed.