Neutron powder diffraction studies on Ba3Ca1+xNb2-xO9-3x/2-complex perovskite-type oxides

摘要

High-resolution neutron powder diffraction data were collected on the Ba3Ca1+xNb2-xO9-3x/2 (x=0.10, 0.18, 0.25 and 0.35) at room temperature, All the data were precisely refined by the Rietveld method based on several structure models. Considering the variations of bond lengths and polyhedral volumes of [BO6] octahedra, the most suitable structure model for this system was found to be rhombohedral one based on the space group Rim (a approximate to 5.95 Angstrom, alpha approximate to 60.0degrees), which was slightly distorted from the cubic model based on the space group Fm (3) over barm (a approximate to 8.41 Angstrom). (C) 2002 Elsevier Science B.V. All rights reserved. [References: 12]