Charge states of Ca atoms in {beta}-dicalcium silicate
- Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)
- Intense Pulsed Neutron Source Division, Argonne National Laboratory, Argonne, IL 60439 (United States)
- Institute of Applied Beam Science, Graduate School of Engineering and Science, Ibaraki University, 4-12-1 Nakanarusawa-cho, Hitach, Ibaraki 316-8511 (Japan)
- Department of Materials Structure Science, Graduate University for Advanced Studies, Tsukuba, Ibaraki 305-0801 (Japan)
- Department of Engineering Physics and Mechanics, Kyoto University, Kyoto 606-8501 (Japan)
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan)
In order to study the crystal structure of {beta}-bar Ca{sub 2}SiO{sub 4}, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600 deg. C. Rietveld refinement at RT has shown that {beta}-bar Ca{sub 2}SiO{sub 4} is monoclinic based on P2{sub 1}/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3A were calculated, with the valences of Ca(1) with seven Ca-O bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen-Brown-Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in {beta}-bar Ca{sub 2}SiO{sub 4} are [Ca(1)SiO{sub 4}]{sup 2-} and Ca(2){sup 2+}, respectively. Furthermore, the [Ca(1)SiO{sub 4}]{sup 2-} unit has the shortest Ca-O distance, and its length kept constant at 2.23A at all temperatures. In the short-range structure analysis at RT, the shortest Ca-O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO{sub 4}]{sup 2-} unit has covalency on the shortest Ca-O in addition to Si-O.
- OSTI ID:
- 20900872
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 11; Other Information: DOI: 10.1016/j.jssc.2006.06.018; PII: S0022-4596(06)00356-2; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energyncy (IAEA)CALC; ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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