Neutron diffraction and MAS NMR of Cesium Tungstate defect pyrochlores

摘要

Defect-pyrochlores based on the formulation CsM0 W-5(1) O-5(6) (M = Ti, Ti/Zr, Zr and Hf) have been studied using neutron diffraction and magic-angle spinning nuclear magnetic resonance (MAS NMR). The results show that structural changes are linearly linked to the change in ionic-radius for the B-site, e.g. the unit cell changes from 10.2763 angstrom for CsTi0.5W1.5O6 to 10.3820 angstrom for CsZr0 W-4(1) O-6(6). Changes in the NMR chemical shift correlate with the change in electronegativity on the B-site, and show the presence of only one Cs crystal site. (C) 2005 Elsevier Inc. All rights reserved.