Octahedral cations in Rb₃C₆₀: Reconciliation of conflicting evidence from different probes

¹ Department of Physics, State University of New York, Stony Brook, NY 11794-3800 USA
² National Synchrotron Light Source, Brookhaven National Lab, Upton, NY 11973 USA
³ Department of Materials Science and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104-6272 USA

Received: 14 July 1997
Accepted: 8 January 1998

Abstract

There is an apparent contradiction between X-ray diffraction, NMR and extended X-ray-absorption fine-structure (EXAFS) measurements on the structure of . Specifically, a possible displacement of the octahedral alkali cations away from their site center and the origin of a third observed Rb NMR line have been widely discussed. We address this question with X-ray powder diffraction as a function of temperature and find that the octahedral cation does have its equilibrium position at the site center with a large Debye-Waller factor. We show how this result can be reconciled with results of NMR and EXAFS.