Temperature dependent neutron powder diffraction study of Bi3(GaSb2)O11

The structure of Bi-3(GaSb2)O-11 as a function of temperature (10 less than or equal to T less than or equal to 295 K) has been refined from powder neutron diffraction data using a Rietveld analysis. No structural phase transitions were observed in the range 10-295 K. The structure of Bi-3(GaSb2)O-11 was refined in space group Pn (3) over bar. The Atomic Displacement Parameters (ADP) of the one of the Bi atoms, Bi(1), were both large and anisotropic. It was determined from the temperature variation that this is due to a positional site disorder and the open geometry. A disordered model, involving splitting the Bi(1) atoms around its 3 fold axis, was found to significantly improve the structural refinements. (C) 1998 Elsevier Science Ltd. All rights reserved.