Enhancement of LaMnO₃ via Strontium Doping for Improved Thermoelectric Applications

Thermoelectric materials have become the recent area of research interest with promising significance to remedy the global crisis of heat waste from industries, homes, and transport systems. They can convert heat waste into electricity by establishing a temperature gradient, which provides a transport mechanism for charge carriers to move within a material. This present research enhanced and investigated the electrical and thermal conductivity through nano-structuring and controlled A-site doping. The synthesis of (La₁₋ₓSrₓMnO₃) perovskites was performed using Sol–gel methods. The characteristics of the synthesized La₀.₈Sr₀.₂MnO₃ was evaluated using thermogravimetric analysis and differential thermal analysis (TGA-DTA), ultraviolet visible spectroscopy (UV–Vis) and electrical conductivity measurements. TGA-DTA results showed multi-stage decomposition typical of nitrate-based precursors and confirmed that the material achieved thermal stability after calcination. Thermal conductivity value was moderately low (11.88 W/mK), while electrical conductivity increased with temperature and was consistent with small-polaron hopping.  XRD confirmed the formation of rhombohedral perovskite structures with average crystallite sizes of 40 nm, indicating successful nanostructuring in both samples. TEM and SEM micrographs revealed nanoscale grains and significant grain-boundary density, which contribute to phonon scattering and reduced thermal conductivity. Thus, the results show that Sr-doping and nano-structuring significantly influence transport properties and confirm that La₁₋ₓSrₓMnO₃ is a promising and environmentally friendly material for high-temperature thermoelectric applications.