Effect of mechanical activation on the thermoelectric properties of Sr1-xSmxTiO3 ceramics
The Sr1-xSmxTiO3 (х = 0.025, 0.05, 0.075, 0.1, 0.2) strontium titanate solid solutions were prepared from oxides and carbonates using a conventional ceramic technology based on the mechanochemical activation. The electrical conductivity and Seebeck coefficient of the synthesized compounds were measured in the temperature range from 300 to 800 K. We found that the properties of the samples significantly depend on the preliminary mechanochemical activation. The thermoelectric power factor attains maximum value in the hydrogen reduced samples with concentration of х = 0.05 and 0.075 obtained from nanoparticles: 5.5 μW/(cm · K2) for Sr0.95Sm0.05TiO3 (580 K) and 4.10 μW/(cm · K2) for Sr0.925Sm0.075TiO3 (650 K). An increase in the annealing temperature of mechanically activated samples leads to an even greater increase in electrical conductivity and power factor: 9.2 μW/(cm · K2) for Sr0.925Sm0.075TiO3 (650 K).