Powder neutron diffraction study of the nonstoichiometric solid solution of lithium tantalate 9LiTaO3:Ta2O5

The nonstoichiometric solid solution 9LiTaO3:Ta2O5 has been studied with the powder neutron diffraction technique, and the intensity data have been used to refine several structural models with the Rietveld method. The results of these calculations show that the best fit to the experimental observations is obtained with the model for the defective structure proposed by Nassau and Lines [J. Appl. Phys. (1970), 41, 533-537] (Rsub(n) = 4.37, Rsub(p) = 6.91, Rsub(w) = 9.34, Rsub(e) = 5.58 for 2964 observations). Data have also been collected from stoichiometric LiTaO3, and the results of the refinement of this structure (Rsub(n) = 3.64, Rsub(p) = 6.97, Rsub(w) = 9.70, Rsub(e) = 5.63 for 2725 observations) agree well with those obtained with single-crystal diffraction techniques. (Auth.)