Influence of Sintering Temperature and Mixing Method on the Structure, Microstructure, and Electrical Properties of La0.7Ba0.3MnO3 Manganites

Abstract

The electrical behavior in manganites compound is strongly affected by the synthesis routes and methods. Previous works have shown that microstructure formation will affect the electrical transport properties of manganite compounds. In this work, the effects of sintering temperature on the structural, microstructural, and electrical properties of La_0.7Ba_0.3MnO₃ (LBMO) samples prepared by mortar grinding (LBMO(A)) and direct glass rod stirring (LBMO(B)) were explored. TGA analysis of the precursor revealed three main weight-loss stages corresponding to dehydration, decomposition of acetate and nitrate groups, and solid-state reactions, indicating that complete phase formation begins above 650°C. XRD results showed that LBMO(A) samples sintered at 900-1000 °C contained secondary phases, while LBMO(B) exhibited a single-phase perovskite structure across all sintering temperatures, indicating better crystallinity. SEM observations revealed grain growth and densification with increasing temperature, with LBMO(A) developing gradually and showing partial melting at higher sintering temperatures, while LBMO(B) densified more rapidly, forming larger and well-connected grains. Temperature-dependent resistivity measurements showed the typical metal-insulator transition, with LBMO(B) exhibiting lower resistivity and higher T_MI, attributed to improved grain connectivity and reduced porosity. Overall, the study highlights the importance of the synthesis mixing method and sintering temperature in optimizing phase purity, microstructure, and electrical behavior of LBMO manganites.