Oxygen Plasma-Induced Modification of Structural and Electrical Properties of Pr_0.5Sr_0.5MnO₃ Manganites

Herein, the impact of exposing the perovskite compound Pr_0.5Sr_0.5MnO₃ to oxygen plasma is explored by comparing the structural and transport properties of the exposed samples to those of the unexposed ones. The Pr is oxidized to PrO₂ in the investigated samples due to plasma exposure. The alterations in the transport properties can be linked to the changes in MnOMn bond angle and Mn-O bond length due to plasma exposure, as indicated by X-ray diffraction analysis. Additionally, exposure to oxygen plasma increases the conductivity by incorporating oxygen into the exposed samples, making them oxygen-rich. Detailed analysis of the resistivity and thermoelectric power data indicates that small polarons are responsible for conduction at high temperatures, while at low temperatures, variable range polarons take over. The negative value of the thermopower at all temperatures proclaims that the electrons behave as the dominant charge carriers.