In situ high-temperature X-ray powder diffraction study of the synthetic Ca<sub>2</sub>Sb<sub>2</sub>O<sub>7</sub> weberite-type compound
DOI:
https://doi.org/10.2451/2011PM0012Keywords:
weberite, Ca2Sb2O7, X-ray powder diffraction, Rietveld refinements.Abstract
Periodico di Mineralogia (2011), 80, 1 (Special Issue), 145-153 - DOI: 10.2451/2011PM0012
Special Issue in memory of Sergio Lucchesi
In situ high-temperature X-ray powder diffraction study of the synthetic Ca2Sb2O7 weberite-type compound
Laura Chelazzi1, Tiziana Boffa Ballaran2, Luca Bindi3, 4 and Paola Bonazzi1, 4,*
1Dipartimento di Scienze della Terra - Università di Firenze, Italy
2Bayerisches Geoinstitut, Universität Bayreuth, Germany
3Museo di Storia Naturale, Sezione di Mineralogia, Università di Firenze, Italy
4C.N.R. - Istituto di Geoscienze e Georisorse - Sezione di Firenze, Italy
*Corresponding author: paola.bonazzi@unifi.it
Abstract
The crystal structure of synthetic Ca2Sb2O7 has been investigated by in situ X-ray powder diffraction methods within the temperature range 298-1273 K. Ca2Sb2O7 is orthorhombic, space group Imma, over the entire temperature range and shows only general thermal expansion. The unit-cell parameters show a monotonous increase as a function of temperature. Only slight changes occur in the individual bond distances without evidence of abrupt structural changes. The mean coefficients of thermal expansion along the various axes are: αa = 9.49 x 10-6 K-1, αb = 10.11 x 10-6 K-1, αc = 7.56 x 10-6 K-1 and the bulk thermal expansion coefficient αV = 27.20 x 10-6 K-1.
Key words: weberite; Ca2Sb2O7; X-ray powder diffraction; Rietveld refinements.
