KSm(MoO4)2, an incommensurately modulated and partially disordered scheelite-like structure

• Published in: Acta Crystallographica B, vol. 64, p. 160-171
• Publication date: 2008

The incommensurately modulated scheelite-like KSm(MoO4)2 structure has been refined in the monoclinic superspace group I2/b(ab0)00 by the Rietveld method on the basis of synchrotron radiation powder diffraction data. The systematic broadening of satellite reflections has been accounted for by applying anisotropic microstrain line-broadening. The microstructure has been studied by transmission electron microscopy (TEM). The partial disorder of the K and Sm cations in the A position is best approximated by a combination of harmonic and complex crenel functions with (0.952Sm + 0.048K) and (0.952K + 0.048Sm) atomic domains. This combination yields a compositional wave distribution from {KMoO4} to {SmMoO4} observed in the ab structure projection along q. The specific features of KSm(MoO4)2 and degree of the A-cation ordering are discussed in comparison with the previously reported structure of KNd(MoO4)2.

Keywords: incommensurately modulated structure ; occupation modulation ; degree of ordering ; scheelite-like structures ; anisotropic microstrain line-broadening

Reference

• LCR-ARTICLE-2008-016
• doi:10.1107/S0108768108001870
• View record in Web of Science

Record created on 2008-03-18, modified on 2012-03-21