The crystal chemistry of Bi{sub 6}TP{sub 2}O{sub 15+x}, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi{sub 6}TiP{sub 2}O{sub 16}
- Department of Chemical Engineering and Texas Materials Institute, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712 (United States)
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States)
The crystal structures of compounds with nominal compositions Bi{sub 6}FeP{sub 2}O{sub 15+x} (I), Bi{sub 6}NiP{sub 2}O{sub 15+x} (II) and Bi{sub 6}ZnP{sub 2}O{sub 15+x} (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5)A, {beta}=96.154(4){sup o}; for (II) a=11.259(7), b=5.461(4), c=11.109(7)A, {beta}=96.65(1){sup o}; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6)A, {beta}=131.932(1){sup o}. Least squares refinements on F{sup 2} converged for (I) to R1=0.0554, wR{sub 2}=0.1408; for (II) R{sub 1}=0.0647, wR{sub 2}=0.1697; for (III) R{sub 1}=0.0385, wR{sub 2}=0.1023. The crystals are complexly twinned by 2-fold rotation about [101-bar], by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi{sub 4} tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO{sub 4} moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350K. Between 4.2 and 250K it is paramagnetic, {mu}{sub eff}=6.1{mu}{sub B}; a magnetic transition occurs above 250K.
- OSTI ID:
- 21015801
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 4; Other Information: DOI: 10.1016/j.jssc.2007.02.018; PII: S0022-4596(07)00084-9; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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