Influence of trivalent lanthanides substitution on the thermoelectric properties of nanostructured Ca1−xLn3 +xMnO3−δ (Ln3+ = Sm, Ce, La; x = 0, 0.1).

Mesoporous Ca_1−xLn^{3 +}_xMnO₃ (Ln³⁺ = Sm, Ce, La; x = 0, 0.1) nanoparticles were prepared by sol–gel hydrothermal method followed by annealing under oxygen atmosphere at 950 °C. The systematic analysis revealed that due to the influence of lanthanides substitution, significant changes were occurring on the electrical and thermoelectric properties of the material. The synthesized nanopowders were characterized by XRD, Raman analysis, SEM with EDAX, HRTEM and thermoelectric measurement. Structural analysis confirmed the orthorhombic perovskite structure without distortions and the cell volume increased with a rise in the ionic radius of the Ln³⁺ ions. Microstructure and EDAX analysis demonstrated the grain size and stoichiometry of all the samples. HRTEM analysis is used to measure the size and shape of the nanoparticles. The physical properties of Ca_0.9Ln³⁺_0.1MnO₃ nanoparticles exhibit metallic behavior with increasing temperature whereas undoped CaMnO₃ shows semiconducting behavior. The electrical and thermoelectric measurements proved that Ca_0.9Sm_0.1MnO₃ nanoparticle showed high Seebeck coefficient value, large electrical resistivity, and significant power factor, indicating a potential n-type thermoelectric material at elevated temperature. [ABSTRACT FROM AUTHOR]