Electrical transport properties of Pr 1−x Sr x MnO 3 ( x = 0 to 0·45)

Abstract

The electrical transport properties of polycrystalline Pr_1−xSr_xMnO₃ (x = 0 to 0·45) perovskite manganites prepared by the solid state reaction method have been studied. The insulator-metal transition temperature T_im shifted to higher temperatures when Sr content was increased. Generally, the average grain size decreased with increase in Sr content. The resistivity versus temperature curves in the metallic (ferromagnetic) and insulating (paramagnetic) region were fitted with several models. The activation energy of electrons hopping and the density of states at the Fermi level were estimated from the curve fitting. The ρ-T² curve was found to be nearly linear in the metallic region, but the ρ-T^2·5 curve deviated from linearity for x = 0·2 and 0·33. The variable range hopping model and small polaron hopping models fit well in the high temperature region. Sr substitution led to the decrease in the activation energy and the T_o values.