Influence of the structural disorder and applied bias voltage variations on the hopping conduction mechanisms, scattering processes, and temperature coefficient of resistance characteristics of Sm0.55-xPrxSr0.45MnO3 (0≤x≤0.4) ceramics

The influence of the Praseodymium content and the applied bias voltage on the structural properties, scattering processes, electrical conduction, and the temperature coefficient of resistance characteristics of Sm0.55-xPrxSr0.45MnO3 (0.0≤x ≤ 0.4) ceramics has been discussed. At room temperature, the refined X-ray diffraction data confirmed that the prepared compounds crystallize in the distorted orthorhombic system with a Pbnm space group. In addition, the structural study proves the single-phase nature of all the substituted Sm0.55-xPrxSr0.45MnO3 (0.1≤x ≤ 0.4) compounds without any detectable impurities. By increasing the Praseodymium content, it is observed that the A-site cationic size disorder has decreased from σ2 (x = 0.0) = 8.019 × 10−3 Å2 to σ2 (x = 0.4) = 5.3602 × 10−3 Å2. The electrical resistivity study confirmed the strong impact of cationic disorder variation on the dynamics of charge carriers and Mn–Mn cation interactions. It is worth mentioning that all of the prepared compounds demonstrate maximum resistivity at a well-defined transition temperature TM-S. The transition temperature has shifted towards 240 K for x = 0.4, indicating a clear trend in the data. Below TM-S, the metallic behavior of the materials is related to the electron bandwidth competition and size disorder effects. The aforementioned effects are being examined concerning the scattering processes between electron, phonon, and magnon interactions. Beyond TM-S, the electrical resistivity decrease has been attributed to the electron bandwidth increase. The enhanced conduction and the appearance of a semiconductor behavior have been attributed to the activation of the small polaron hopping and variable range hopping mechanisms. The results show that the studied ceramics exhibit both positive and negative temperature coefficient of resistance (TCR) characteristics that depend mainly on the cationic disorder and the bias voltage effects. The maximum TCR value has been observed for Sm0.45Pr0.1Sr0.45MnO3 after applying a bias voltage value of 1V. •Electrical resistivity responses.•Hopping of charge carrier's and scattering processes.•Influence of the cationic disorder on the resistivity variations.•Applications of the manganites as thermo-sensitive ceramics.