[Open access]

Acta Cryst. (2013). E69, i36
[ doi:10.1107/S1600536813012191 ]

The low-symmetry lanthanum(III) oxotellurate(IV), La10Te12O39

P. L. Wang and Y. Mozharivskyj

Abstract: Single crystals of decalanthanum(III) dodecaoxotellurate(IV), La10Te12O39, were obtained by reacting La2O3 and TeO2 in a CsCl flux. Its crystal structure can be viewed as a three-dimensional network of corner- and edge-sharing LaO8 polyhedra with TeIV atoms filling the interstitial sites. The TeIV atoms with their 5s2 electron lone pairs distort the LaO8 polyhedra through variable Te-O bonds. Among the six unique Te sites, four of them define empty channels extending parallel to the a axis. The formation of these channels is a result of the stereochemically active electron lone pairs on the TeIV atoms. The atomic arrangement of the Te-O units can be understood on the basis of the valence shell electron pair repulsion (VSEPR) model. A certain degree of disorder is observed in the crystal structure. As a result, one of the five different La sites is split into two positions with an occupancy ratio of 0.875 (2):0.125 (2). Also, one of the oxygen sites is split into two positions in a 0.559 (13):0.441 (13) ratio, and one O site is half-occupied. Such disorder was observed in all measured La10Te12O39 crystals.

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