Synchrotron study of the garnet-type oxide Li(6)CaSm(2)Ta(2)O(12).

Hexalithium calcium disamarium(III) ditantalum(V) dodeca-oxide, Li(6)CaSm(2)Ta(2)O(12), crystallizes in a cubic garnet-type structure. In the crystal structure, disordered Li atoms occupy two crystallographic sites. One Li has a tetra-hedral coordination environment in the oxide lattice, whereas the other Li atom occupies a significantly distorted octa-hedral site, with site occupancies for the two Li atoms of 0.26†(7) and 0.44†(2), respectively. Ca and Sm atoms are statistically distributed over the same crystallographic position with a occupancy of 2/3 for Sm and of 1/3 for Ca, and are eightfold coordinated by O atoms. The TaO(6) octa-hedron is joined to six others via corner-sharing LiO(4) tetra-hedra. One Li and the O atoms lie on general positions, while the other atoms are situated on special positions. The Sm/Ca position has 222, Ta has , and the tetra-hedrally coordinated Li atom has site symmetry.