Investigation of nanostructured Strontium titanate based oxide Thermoelectric materials for energy Harvesting from waste heat

Abstract

The rapidly increasing global warming stimulated the researchers to find an alternate way for generating electricity instead of burning the fossil fuel. Moreover, the demand for electrical energy is rapidly growing due to increasing world population and curtailment of conventional energy sources. Thermoelectrics is a promising technology to convert the waste heat into electricity. Therefore, highly efficient thermoelectric materials need to be developed for effectively converting the waste heat into electricity which will solve the environmental problem and energy demand. Thermoelectric performance of a material can be determined by a Figure of Merit. Nanostructuring of a material is an effective approach to improve the thermoelectric performance of a material. In the nanostructured materials, the phonons get scattered at the grain boundaries. On the other hand, oxide thermoelectric materials have attracted great attention due to their high thermal stability and easy preparation process when compared to semiconductor materials. NaCoO3 and CaCoO3 are the well-known oxide thermoelectric materials with reasonably high performance due to their layered structures. Recently, perovskite based materials have been attracted by the researchers for thermoelectric applications due to their tunable properties. Optimizing the doping elements and their concentrations along with introducing point defects are the appropriate approaches for reducing the thermal conductivity and enhancing power factor of perovskite based oxide materials. SrTiO3, a well-known perovskite material has been extensively investigated for thermoelectric applications. In this thesis, the effect of substitution of heterovalence elements at A-site, co-substitution of elements with different ionic radius at A and B sites and addition of graphene oxide on the structural, morphological and thermoelectric properties were studied newline