Microstructure control on thermoelectric properties of Ca0.96Sm0.04MnO3 synthesised by co-precipitation technique

Nanopowder of Ca0.96Sm0.04MnO3 (CSM) perovskite was prepared by chemical co-precipitation technique. It was characterized and studied by X-ray diffraction and Transmission Electron Microscopy. Nano-crystalline CSM phase having grain size of 60–70 nm can be prepared by calcination at 1073 K for 6 h in air. The obtained nanopowder was pressed, sintered at 1373 K for 24 h to obtain a dense sample. In comparison, CSM samples prepared from normal powder need sintering temperature of 1623 K to reach a similar microstructure, showing the efficiency of nanopowder to decrease the sintering temperature. The thermoelectric properties of samples prepared with two different processes were studied. The Seebeck coefficient and the thermal conductivity slightly decrease by using the nanopowder while the value of the electrical resistivity does not change. This results in the same figures of merit for the two materials.