Li(2)Ca(1.5)Nb(3)O(10) from X-ray powder data.

Lithium calcium niobium oxide (2/1.5/3/10), Li(2)Ca(1.5)Nb(3)O(10), has been synthesized by conventional solid-state reaction. Its structure consists of triple-layer perovskite slabs of corner-sharing NbO(6) octa-hedra inter-leaved with lithium ions; Ca cations partially occupy the perovskite A sites at 75% occupancy probability. All eight atoms in the asymmetric unit are on special positions: one Nb atom has site symmetry 4/mmm; the second Nb, both K, the Sr and two O atoms have site symmetry 4mm; the remaining two O atoms have site symmetries 2mm. and mmm., respectively.