Comparison of the crystal structures of [gamma]-Bi[sub 2]MoO[sub 6] and Bi[sub 2]WO[sub 6]

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1016/0022-4596(92)90186-Y· OSTI ID:6838940

Thompson, J G; Schmid, S; Withers, R L; Fitz Gerald, J D ^[1]; Rae, A D ^[2]

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1. Australian National Univ., Canberra (Australia)
2. Univ. of New South Wales, Kensington (Australia)

In previous crystal structure studies on each of these compounds the only analogy drawn between the two was by Theobald et al., who recognized the similar unit cell dimensions but who noted that the reported space group, B2ab(6), was different from all the possible space groups previously considered for [gamma]-Bi[sub 2]MoO[sub 6]. The crystal structure of [gamma]-Bi[sub 2]MoO[sub 6], koechlinite, is compared with the recently re-refined structure of Bi[sub 2]WO[sub 6], russellite. Appropriate resetting of the atomic coordinates of [gamma]-Bi[sub 2]MoO[sub 6] showed the structures to be isomorphous. Symmetry decomposition of these structures shows the major displacive modes to be virtually identical. The magnitude and/or sign of some of the minor displacive modes, however, are not in agreement. The advantages of X-ray diffraction data over neutron powder data for the refinement of these minor modes are discussed. Transmission electron microscope evidence is presented for the existence of a minority B1a1 component coherently intergrown with the majority P2[sub 1]ab structure in [gamma]-Bi[sub 2]MoO[sub 6], as also observed in Bi[sub 2]WO[sub 6]. To obtain evidence of the recently reported structural phase transition in Bi[sub 2]WO[sub 6] at [approx]15[degree]C, diffraction patterns and images of this material were recorded at low temperature. The coherent intergrowths were still found to occur at low temperature.

• OSTI ID: 6838940
• Journal Information: Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 101:2; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
BISMUTH COMPOUNDS
BISMUTH OXIDES
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
EVALUATION
FERROELECTRIC MATERIALS
MICROSCOPY
MINERALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NEUTRON DIFFRACTION
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REFRACTORY METAL COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES
VALENCE
X-RAY DIFFRACTION