Structural and impedance spectroscopy properties of Pr0.6Sr0.4Mn1-xTixO3±δ perovskites

An exhaustive study of structural, dielectric and impedance analysis on Pr0.6Sr0.4Mn1-xTixO3 +/-delta (0 <= x <= 0.4) perovskites were performed. Polycrystalline samples were prepared using solid state reaction method. The crystallographic structure was studied by X-ray diffraction experiments and Rietveld refinement revealed that all samples crystallize in an orthorhombic structure with Pnma space group. The approximate grain size was found from experiments' scanning electron microscopy. The electrical response was studied using the impedance spectroscopy technique over a broad frequency range (0.1 Hz-1 MHz). The values of total conductivity for all samples were well fitted by the Jonscher law sigma(tot)(-omega) = sigma(dc) + A omega(n). For 0 <= x <= 0.3 samples, the hopping process occurs through long distance, whereas for x = 0.4 compound the hopping occurs between neighboring sites. The Pr0.6Sr0.4Mn0.6Ti0.4O3 +/-delta sample presents the lowest real part Z' and the highest dc-conductivity sigma(dc) among these samples. For x = 0.3 and 0.4 compounds, the variation of the imaginary part Z '' shows a peak at a relaxation frequency related to the relaxation time (tau) by tau = 1/2 pi f(r). Nyquist plots of impedance show semicircle arcs for samples beyond 20% Ti content and an electrical equivalent circuit has been proposed to explain the impedance results. (c) 2013 Elsevier B.V. All rights reserved.