Synchrotron X-ray study of noncentrosymmetric Tb(3)RuO(7) with partial structural disorder.

ABSTRACT

Single-crystal synchrotron X-ray diffraction reveals partial structural disorder of Tb atoms at 293 K in flux-grown Tb(3)RuO(7) (triterbium ruthenium heptaoxide) crystals. The structure is noncentrosymmetric and composed of infinite single chains of corner-linked RuO(6) octahedra embedded in a Tb(3)O matrix. Two Tb atom sites out of the six crystallographically independent Tb sites are split into two positions. The split sites are separated by approximately 0.3-0.4 Angstrom, with slightly different coordination environments. The RuO(6) octahedra in the present P2(1)nb modification have two tilt systems about the a and c axes, in contrast with a single tilt about c in the other Cmcm modifications of Ln(3)RuO(7) (Ln = lanthanoid elements).