Structural Behavior, Microstructure Evolution and Electrical Properties of Pr0.7Sr0.3MnO3 Synthesized by Thermal Decomposition Method under Different Sintering Temperatures

Abstract

This study investigates the influence of sintering temperature (900–1400 °C) on the structural, microstructural, and electrical properties of bulk Pr_0.7Sr_0.3MnO₃ (PSMO) synthesized via a thermal decomposition method under ambient conditions. X-ray diffraction (XRD) analysis confirmed the formation of orthorhombic PSMO with a perovskite structure and space group Pnma (62) for all samples, while secondary PrMn₂O₅ phases were detected in samples sintered at 900 °C and 1000 °C. Single-phase PSMO was successfully achieved at sintering temperatures of 1100 °C and above. Scanning electron microscopy (SEM) revealed progressive grain growth and enhanced intergranular connectivity with increasing sintering temperature. Temperature-dependent resistivity measurements showed that the metal–insulator transition temperature (T_MI) increased from 230 K for the sample sintered at 900 °C to 240 K, 266 K, 268 K, 274 K, and 276 K for samples sintered at 1000, 1100, 1200, 1300, and 1400 °C, respectively, accompanied by a substantial reduction in resistivity. The highest resistivity of 1.60 Ω·cm was observed for the sample sintered at 900 °C, whereas the lowest peak resistivity of 2.59  10^-3 Ω·cm was obtained for the sample sintered at 1400 °C. The improved electrical performance at higher sintering temperatures is attributed to enhanced crystallinity, increased grain size, improved grain connectivity, and reduced electron scattering at grain boundaries. Overall, the sample sintered at 1400 °C exhibited the most favorable combination of phase purity, microstructural development, and electrical transport properties, indicating that this temperature provides the optimum processing condition for PSMO synthesized via thermal decomposition.