Potassium Disorder in the Defect Pyrochlore KSbTeO6: A Neutron Diffraction Study
José Antonio Alonso,
Sergio Mayer,
Horacio Falcón,
Xabier Turrillas,
María Teresa Fernández-Díaz
Affiliations
José Antonio Alonso
Instituto de Ciencia de Materiales de Madrid Consejo Superior de Investigaciones Científicas., Cantoblanco, E-28049 Madrid, Spain
Sergio Mayer
Nanotech (Centro de Investigación en Nanociencia y Nanotecnología), Universidad Tecnológica Nacional-Facultad Regional Córdoba, 5016 Córdoba, Argentina
Horacio Falcón
Nanotech (Centro de Investigación en Nanociencia y Nanotecnología), Universidad Tecnológica Nacional-Facultad Regional Córdoba, 5016 Córdoba, Argentina
Xabier Turrillas
Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas, Bellaterra, E-08193 Barcelona, Spain
María Teresa Fernández-Díaz
Institut Laue Langevin, BP 156X, F-38042 Grenoble, France
KSbTeO6 defect pyrochlore has been prepared from K2C2O4, Sb2O3, and 15% excess TeO2 by solid-state reaction at 850 °C. Direct methods implemented in the software EXPO2013 allowed establishing the basic structural framework. This was followed by a combined Rietveld refinement from X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) data, which unveiled additional structural features. KSbTeO6 is cubic, a = 10.1226(7) Å, space group F d 3 ¯ m , Z = 8 and it is made of a mainly covalent framework of corner-sharing (Sb,Te)O6 octahedra, with weakly bonded K+ ions located within large cages. The large K-O distances, 3.05(3)–3.07(3) Å, and quite large anisotropic atomic displacement parameters account for the easiness of K+ exchange for other cations of technological importance.
