Metal–semiconductor transition in non-stoichiometric double perovskite Sr2FexMo2−xO6

The electronic transport properties of the ordered double perovskite oxides Sr2FexMo2−xO6 (<f>0.8&les;x&les;1.5</f>) have been investigated. In this system, the samples (<f>x&ges;1.2</f>) are semiconducting in the temperature range of <f>4.2&les;T&les;300</f> K. A metal–semiconductor transition occurs when <f>x<1.2</f> and the transition temperature <f>TMS</f> decreases obviously as the Fe content decreases. Rietveld refinement of the X-ray powder diffraction profiles indicates that the crystal structure of the compounds Sr2FexMo2−xO6 changes from a tetragonal I4/mmm lattice to a cubic <f>Fm3¯m</f> lattice around <f>x=1.2</f>. [Copyright &y& Elsevier]