Structural transition and atomic ordering in the non-stoichiometric double perovskite Sr2FexMo2−xO6

The structural transition and atomic ordering of a new series of ordered double perovskite oxides Sr2FexMo2−xO6 (0.8≤x≤1.5) have been studied by X-ray powder diffraction (XRD). Rietveld refinement of the powder diffraction profiles indicates that the crystal structure of the compounds Sr2FexMo2−xO6 changes from a tetragonal <F>I4/mmm</F> lattice to a cubic <F>Fm3¯m</F> lattice around <F>x=1.2</F> and the lattice parameters decrease slightly as Fe content increases. The degree of ordering in Sr2FexMo2−xO6 exhibits a maximal at <F>x=0.95</F> and decreases as <F>x</F> deviates from 0.95. [Copyright &y& Elsevier]