Neutron diffraction and MAS NMR of Cesium Tungstate defect pyrochlores

Defect-pyrochlores based on the formulation CsM0.5W1.5O6 (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 Å for CsTi0.5W1.5O6 to 10.3820 Å for CsZr0.4W1.6O6. 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.

Unit cell representation of CsTi0.5W1.5O6, projection of the [110] plane. Yellow spheres are Cs+, red spheres are O2− and blue spheres are the B-site.Figure optionsDownload as PowerPoint slide