SrSeO3 from a combined X-ray and neutron powder diffraction study

Strontium trioxoselenate(IV), SrSeO3, crystallizes in the KClO3 structure type and is isotypic with BaSeO3, beta-PbSeO3 and the mineral scotlandite (PbSO3). The Sr2+ cation is nine-coordinated by O atoms. The SrO9 polyhedra are linked together by common edges to form a three-dimensional network, with channels running along the b axis where the Se4+ cations reside. They are coordinated by three O atoms to form one-sided SeO3E pyramids (E = electron lone pair), with Se - O bond lengths of 1.672 ( 6) and 1.688 ( 3) angstrom ( x 2). The SeO3E pyramids are not connected to each other; instead, they share O atoms with the SrO9 polyhedra. Except for one O atom, all other atoms (one Sr, one Se and the second O atom) are located on mirror planes.