| Autor: |
S.J. Patwe, Srungarpu N. Achary, M.D. Mathews, Avesh K. Tyagi |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
Journal of Physics and Chemistry of Solids. 67:774-781 |
| ISSN: |
0022-3697 |
| DOI: |
10.1016/j.jpcs.2005.11.009 |
| Popis: |
In this communication, the high temperature crystal chemistry of scheelite type (space group: I 4 1 / a ) CaMoO 4 (powellite) is reported. The details of the high temperature crystal structures were obtained by high temperature X-ray diffractometer (HT-XRD) data in the temperature range of 25–1000 °C. The lattice thermal expansions of this compound show the an-isotropic behavior, with the coefficient of thermal expansion along c -axis ( α c ) is almost double of that along the a -axis ( α a ). The average values of thermal expansion coefficient for CaMoO 4 are: α a =13.5×10 −6 and α c =22.8×10 −6 °C. The typical thermal expansion behavior is basically controlled by the temperature-induced expansion of the Ca–O bonds, i.e. by the thermal expansion of the CaO 8 polyhedra. The MoO 4 polyhedra acts as typical rigid unit, with virtually no expansion. The preliminary data analysis for CaWO 4 indicates almost similar values of thermal expansion coefficients, viz. α a =12.7×10 −6 and α c =21.4×10 −6 /°C (for CaWO 4 ) in the same temperature range. The further details are explained in this manuscript. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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