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Polymorphism in Bi{sub 5}Pb{sub 3}O{sub 10.5}

Journal Article · · Journal of Solid State Chemistry
; ;  [1];  [2];  [3]
  1. National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan)
  2. ENSCL et USTL, Villeneuve d`Ascq (France). Lab. de Cristallochimie et Physicochimie du Solide
  3. Univ. of Waikato, Hamilton (New Zealand). Centre for Technology
This paper describes the phase and structural relations between three polymorphs of Bi{sub 5}Pb{sub 3}O{sub 10.5}. The low-temperature stable phase named {beta}{sub L} crystallizes in the triclinic system with a = 14.903(1) {angstrom}, b = 14.184(1) {angstrom}, c = 7.2115(7) {angstrom}, {alpha} = 97.216(8){degree}, {beta} = 118.434(6){degree}, {gamma} = 80.647(8){degree}, and Z = 4. The unquenchable high-temperature stable phase labeled {beta} forms a solid solution and has an anti-{alpha}-AgI-type structure with the space group Im3m; {beta}-Bi{sub 5}Pb{sub 3}O{sub 10.5} has a = 4.40 {angstrom} at 600 C and Z = 2 (Bi{sub 5/8}Pb{sub 3/8}O{sub 10.5/8}). The metastable phase termed {beta}{sub 2} also forms a solid solution and crystallizes in the tetragonal system with the possible space group P4{sub 2}/n; {beta}{sub 2}-Bi{sub 5}Pb{sub 3}O{sub 10.5} has a = 12.132(1) {angstrom}, c = 20.059(2) {angstrom}, and Z = 9. The {beta}{sub L} phase transforms to the {beta} phase at about 585 C; on subsequent cooling, at about 560 C, the {beta} phase changes to the {beta}{sub 2} phase which is kept to room temperature. The {beta}{sub 2} phase reverts to the {beta}{sub L} phase by annealing at low temperatures, e.g., at 500 C. The structure of {beta}{sub L}-Bi{sub 5}Pb{sub 3}O{sub 10.5} is based on a pseudo-bcc {beta}-type subcell, and the transformation matrix is ({minus}2, 2, 2)/(1, {minus}1, 3)/(3/2, {1/2}, {minus}{1/2}). The structure of the {beta}{sub 2} phase is connected to that of red tetragonal PbO-type structure according to (3, 0, 0)/(0, 3, 0)/(0, 0, 4). From the viewpoint of the lone pair of electrons on Bi{sup 3+} and Pb{sup 2+}, the metastability of the {beta}{sub 2} phase is discussed.
OSTI ID:
349932
Journal Information:
Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 144; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English