Crystal structure of Ge_4Se_9:a new germanium selenide with Se_2 pairs breaking the edge-sharing GeSe_4 tetrahedra in GeSe_2

摘要

The crystal structure of the new germanium selenide Ge_4Se_9 has been determined by powder X-ray diffraction. It shows a new feature for this class of compounds; corner sharing of tetrahedra via Se_2 dimers with short se-Se bonds. Structurally, Ge_4Se_9 is related to GeSe_2 in that the edge-sharing tetrahedra in ambient pressure GeSe_2 are split by the introduction of Se_2 pairs.