Contribution of the Rietveld method to non-stoichiometric phase modeling.: Part II:: γ-Tl5Te3 and μ Nb-Ni as experimental examples

Two detailed examples are considered to show the ability of powder diffraction data analyzed with the Rietveld method to get insight into the detailed structure of non-stoichiometric phases. Both the gamma-phase in Tl-Te system and mu-phase in Nb-Ni system were investigated as a function of composition across their whole homogeneity domain. In the case of the gamma Tl-Te phase, the excess Tl relative to the stoichiometric composition is accommodated by Tl substitution on one of the two Te sites. In the mu Nb-Ni, three of the five sites of the structure are partially disordered for all the compositions studied. The results are analyzed in view of Calphad modeling of both phases. (C) 2002 Elsevier Science Ltd. All rights reserved.