Structure refinement of mixed oxides FexCo1-xTa2O6

We report X-ray powder diffraction measurements performed on synthetic samp les of the tapiolite-like FexCo1-xTa2O6 solid solution. The crystal structu re has been refined by the Rietveld method, by using the program FULLPROF. All the samples are tetragonal and were indexed to the space group P4(2)/mn m. The end-members (FeTa2O6 and CoTa2O6) have unit-cell parameters quite si milar to those previously published. The unit-cell parameters a and c for t he mixed samples vary linearly with the cation substitution (Co --> Fe) acc ording to the Vegard's law in all the range of substitution. (C) 2001 Elsev ier Science Ltd. All rights reserved.