Improving of thermoelectric figure of merit in Sr0.925Dy0.075TiO3 ceramics

https://doi.org/10.1016/j.ceramint.2024.10.351

Rare earth doped SrTiO₃ is one of the most promising oxide materials meeting the safety and stability requirements for potential applications in thermoelectric converters. This work aims to assess the feasibility of engineering SrTiO₃-based materials to improve their thermoelectric performance. A comparative analysis of the thermoelectric properties of Sr_0.925Dy_0.075TiO₃ ceramic samples obtained from preliminarily mechanically activated Sr_0.925Dy_0.075TiO₃ nano-powder by two methods – solid-state reaction synthesis and spark plasma sintering – was carried out. Significant differences in the morphology of the samples lead to significant differences in the temperature dependences of electrical resistivity and the Seebeck coefficient. Ceramics obtained by solid-state reaction synthesis exhibit lower porosity and lower electrical resistivity. The thermoelectric power factor of such ceramics is 2–3 times higher than that of samples obtained by spark plasma sintering. The obtained value of thermoelectric figure of merit ZT = 0.41 at T = 673 K for Sr_0.925Dy_0.075TiO₃ is the highest value among n-type oxide thermoelectric ceramics at a given temperature and maintains a tendency to increase with increasing temperature.