Magnetic and transport properties driven by Sr substitution in polycrystalline Pr1-xSrxCoO3(0.1 = x = 0.5) cobaltites

摘要

The effect of strontium (Sr) doping on the structural, magnetic, electrical, and thermal properties of Pr1-xSrxCoO3 (0.1 = x = 0.5) has been studied. The samples were synthesized by using the conventional solid-state reaction method. The Rietveld refinement of X-ray diffraction patterns confirms the single-phase composition with orthorhombic (Pbnm) perovskite symmetry. The magnetization measurements revealed the paramagnetic to ferromagnetic transition and the transition temperature (T-c) increased with increasing Sr doping. The effective magnetic moments determined by the Curie-Weiss law show an increase in the Sr concentration. The temperature dependence of electrical resistivity suppressed with increasing the Sr content. Moreover, all the compounds other than x = 0.5 show the semiconducting nature. All semiconductor compositions (x = 0.1, 0.2, 0.3, and 0.4) in the high temperature region can be explained within the framework of the small polaron hopping model and the variable range hopping model, whereas the metallic composition (x = 0.5) is explained by electron-electron, electron-phonon, and electron-spin fluctuation scattering processes. The Seebeck coefficient (S) for all the samples except x = 0.5 is found to be positive, thereby confirming the applicability of the small polaron hopping model in the high-temperature region. The sample with x = 0.5 exhibits a crossover in S from positive to negative values and again attains a positive value. Published by AIP Publishing.