LOW-TEMPERATURE COPPER ORDERING IN THE LAYERED THIOPHOSPHATE CUVP2S6 - A TIME-OF-FLIGHT NEUTRON POWDER DIFFRACTION STUDY

CuVP2S6 at room temperature is a layered structure with a statistical distribution of copper cations, Cu1, on three different kinds of sites: triangular, tetrahedral, and octahedral. Upon cooling to 20 K, an ordering of the copper has been observed, whereas the low-temperature structure frame remains the same. The tetrahedral and octahedral sites are emptied, with the copper ions located entirely within the sulfur triangles at the edge of the structure slabs. The characteristics of the CuS3, groups are the same as those of the least filled room-temperature sites. © 1993 Academic Press, Inc.