Crystal structure and phase transformations of calcium yttrium orthophosphate, Ca{sub 3}Y(PO{sub 4}){sub 3}
- Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
Crystal structure and phase transformations of calcium yttrium orthophosphate Ca{sub 3}Y(PO{sub 4}){sub 3} were investigated by X-ray powder diffraction, selected-area electron diffraction, transmission electron microscopy and optical microscopy. The high-temperature phase is isostructural with eulytite, cubic (space group I4-bar 3d) with a=0.983320(5)nm, V=0.950790(8)nm{sup 3}, Z=4 and D{sub x}=3.45Mgm{sup -3}. The crystal structure was refined with a split-atom model, in which the oxygen atoms are distributed over two partially occupied sites. Below the stable temperature range of eulytite, the crystal underwent a martensitic transformation, which is accompanied by the formation of platelike surface reliefs. The inverted crystal is triclinic (space group P1) with a=1.5726(1)nm, b=0.84267(9)nm, c=0.81244(8)nm, {alpha}=109.739(4){sup o}, {beta}=90.119(5){sup o}, {gamma}=89.908(7){sup o}, V=1.0134(1)nm{sup 3}, Z=4 and D{sub x}=3.24Mgm{sup -3}. The crystal grains were composed of pseudo-merohedral twins. The adjacent twin domains were related by the pseudo-symmetry mirror planes parallel to {l_brace}101-bar {r_brace} with the composition surface {l_brace}101-bar {r_brace}. When the eulytite was cooled relatively slowly from the stable temperature range, the decomposition reaction of Ca{sub 3}Y(PO{sub 4}){sub 3}->{beta}-Ca{sub 3}(PO{sub 4}){sub 2}+YPO{sub 4} occurred.
- OSTI ID:
- 20900883
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 11; Other Information: DOI: 10.1016/j.jssc.2006.07.013; PII: S0022-4596(06)00384-7; Copyright (c) 2006 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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