Influence of sintering temperature on the electrical and thermal properties of bulk samples of Pr_2/3Sr_1/3MnO_3-δ

We present temperature-dependent studies on electrical and thermal properties of bulk samples of Pr_2/3Sr_1/3MnO_3-δ synthesized at different sintering temperatures (T_S). It is established that these properties intensely influenced by the sintering temperatures. Analysis of electrical resistivity data ρ(T) by means of standard models, demonstrated that electron-electron scattering processes play a key role in the conduction process in the low-temperature region. At high temperatures, the ρ(T) follows the small polaron hopping (SPH) model. Analyses of the Seebeck coefficient data S(T) in the low temperature regime illustrates that electron-magnon scattering governs the thermoelectric transport, on contrary, the high-temperature S(T) follows the SPH model. The low-temperature phonon peak in thermal conductivity κ(T) increases with increasing T_S, demonstrating that a better crystallinity of Pr_2/3Sr_1/3MnO₃ samples was obtained at higher sintering temperatures. Magnetic transitions are observed to increase with a higher T_S, and the entropy change associated with the transition also increases with T_S.