Research Information System
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, vol.31, no.23, pp.20657-20666, 2020 (SCI-Expanded)
The Pr0.67Ba0.22Sr0.11Mn1-xTixO3 (x = 0.05 and 0.075) manganites are synthesized using solid-state reaction route. All XRD patterns with narrow and intense diffraction peaks reveal that the samples are well crystallized. For electrical properties we measure the conductivity versus temperature (80-400 K) and frequencies (40 Hz-10 MHz). These measurements were made by admittance spectroscopy technique. The effect of titanium doping on the electrical properties of our compounds appears by semiconductor behavior. The variation of DC-conductivity with temperature presents two metal-semiconductor transitions. The first transition T-MS bound by Mn3+/Mn4+ ratio but the second transition TSM depends to an extrinsic effect of grain boundaries. It was observed also that the conductivity decreases with titanium concentration, such behavior is associated to a reduction of double-exchange mechanism. The conduction mechanism is explained by thermally activated hopping of small polaron at high temperature range. The activation energy was evaluated of about E-a = 30 m eV for x = 0.05 and Ea = 61 meV for x = 0.075. The total conductance spectrum of Pr0.67Ba0.22Sr0.11Mn0.925Ti0.075O3 compound is well described by the Jonscher power law: G(w) = G(dc) + A omega(n). Impedance study for the sample with x = 0.075 indicates the presence tow metal-semiconductor transitions and a non-Debye relaxation phenomenon related to a grain and grain boundary medium. Also, the modulation of the material by an electrical equivalent circuit show high values of grain boundary medium capacity.