Phase separation region in the phase diagram of polycrystalline Pr_0.65Ca_0.35-xSr_xMnO₃

We have performed measurements of thermoelectric power, electrical resistivity and DC magnetization in polycrystalline samples of Pr_0.65Ca_0.35-xSr_xMnO₃ with x = 0, 0.02, 0.05, 0.10 and 0.20. The system presents an evolution from a charge-ordered manganite at x = 0, with an insulating-like resistivity and low magnetization values, towards a ferromagnetic (FM) metallic state for x = 0.20. We show that in the intermediate region a strong competition between the FM double-exchange and the localized charge-ordering occurs, inducing the phase segregation of the two competing states in a wide temperature range. We estimate the temperature (T) evolution of the FM phase fraction of the x = 0.10 sample and construct a complete T-x phase diagram.