Neutron diffraction and MAS NMR of Cesium Tungstate defect pyrochlores

• Published in: Journal of solid state chemistry 2006-02, Vol.179 (2), p.512-521
• Main Authors: Whittle, K.R., Lumpkin, G.R., Ashbrook, S.E.
• Format: Article
• Language: English
• Subjects: 133Cs MAS NMR; CESIUM COMPOUNDS; CESIUM IONS; CHEMICAL SHIFT; Condensed matter: structure, mechanical and thermal properties; Defect pyrochlore; ELECTRONEGATIVITY; Exact sciences and technology; Inorganic compounds; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NEUTRON DIFFRACTION; Neutron diffraction and scattering; NUCLEAR MAGNETIC RESONANCE; Physics; PYROCHLORE; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; TUNGSTATES; Water, oxides, hydroxides, peroxides
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2005.11.011

Defect-pyrochlores based on the formulation Cs M 0.5W 1.5O 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 Å for CsTi 0.5W 1.5O 6 to 10.3820 Å for CsZr 0.4W 1.6O 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. Unit cell representation of CsTi 0.5W 1.5O 6, projection of the [110] plane. Yellow spheres are Cs +, red spheres are O 2− and blue spheres are the B-site.