Stability and thermoelectric properties of mechano-activated solid solutions of Sr1-xLn xTiO3-? (Ln = Nd, Gd, Dy)

Background: The effect of mechanochemical activation on the microstructure, morphology, and thermoelectric parameters of the materials leading to an increase in the power factor (PF) is demonstrated by the example of the Sr1-xLnxTiO3-8 (Ln = Nd, Gd, Dy; x = 0.05, 0.075, 0.1) solid solutions. Methods: The strontium titanate solid solutions have been synthesized using a conventional ceramic technology from particles of different sizes obtained by mechanical activation of annealed ceramics. Findings: It is shown that different sizes of initial particles cause the morphological and microstructural differences and significantly affect the stability and thermoelectric properties of the synthesized samples. It has been established that a decrease in the initial particle size ensures the thermal stability of the samples and leads to an increase in their electrical conductivity and PF at the minor variation in the Seebeck coefficient. The PF of the Sr0.925Nd0.075TiO3 solid solution changes by a factor of 7. It has been found that the mechanically activated samples have the much lower porosity than the nonactivated ones, which noticeably reduces the effective area of their interaction with the environment (oxygen release and absorption); therefore, all the measurement data obtained on the mechanically activated samples upon their heating and cooling are reversible.

Automated summary

This study demonstrates the effect of mechanochemical activation on the microstructure, morphology, and thermoelectric parameters of Sr1-xLnxTiO3-8 (Ln = Nd, Gd, Dy; x = 0.05, 0.075, 0.1) solid solutions, leading to an increase in the power factor. The results show that different sizes of initial particles cause morphological and microstructural differences, significantly affecting the stability and thermoelectric properties of the synthesized samples. Decreasing the initial particle size enhances the thermal stability of the samples, resulting in increased electrical conductivity and power factor with minor variation in the Seebeck coefficient.