Influence of Cr-Substitution on the Electrical Properties of $Fe_{1-x}Cr_xVSbO_6$

$Fe_{1-x}Cr_xVSbO_6$ solid solution is semiconductor with the activation energy decreasing both in the intrinsic and extrinsic conductivity temperature regions as the Cr-content increases. The n-type conduction is observed for Fe-richer samples while a change of the Seebeck coefficient (from n to p) - for Cr-richer ones. Magnetic isotherms for all samples of solid solution under study are characteristic of the universal Brillouin function, indicating paramagnetic response. These effects are discussed within the framework of the appearance of the mixed valence of both Fe and Cr ions.