Preparation of SrTiO3 Porous Thermoelectric Composite Ceramics under High Pressure and High Temperature

SrTiO3 (STO) is a highly stable and inexpensive perovskite oxide thermoelectric, but phase-pure STO has a low electrical conductivity and high thermal conductivity. This overall poor thermoelectric performance limits its use as a high-temperature thermoelectric. Therefore, suitable methods are needed to enhance the electrical conductivity and reduce the thermal conductivity of STO materials. Compositing STO with materials with a higher conductivity is the most direct way to improve the thermoelectric properties of STO. This paper uses the high pressure and high temperature (HPHT) synthesis method to create an STO composite with Nb to improve the electrical properties. NbN is used to create pores to prepare composite thermoelectric ceramics. Nb in the sample was oxidized to various niobium oxides with thermoelectric properties using HPHT synthesis, and N2 generated during the synthesis of NbN produced pores in the material, which reduced its thermal conductivity and optimized the thermoelectric properties of STO. When the amount of NbN added is x = 0.03, the maximum zT value of 0.295 is obtained at 973 K. This paper provides a method to reduce the thermal conductivity of STO materials to improve their thermoelectric properties by creating voids with NbN during HPHT synthesis.