Crystal and Electronic Structure of La-doped SrTiO\(_3\) and Thermoelectric Properties Modelling based on Single Parabolic Band Fainan Failamani (a), Muhammad Sani Kantaprawira (a), Bambang Prijamboedi (a)*
a) Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology
Jalan Ganesha No. 10, Bandung 40132, Indonesia
*boedi[at]chem.itb.ac.id
Abstract
In order to reduce CO\(_2\) emissions, the conversion of waste heat into electricity by thermoelectric devices has gained significant interest. However, the low efficiency of thermoelectric devices limits their applications. Moreover, most thermoelectric materials consist of toxic and expensive elements. The perovskite-structured material SrTiO\(_3\) (STO) has gained a lot of attention due to its unique band structure and consists of cheap and nontoxic elements. Even though undoped STO is an electrical insulator and possess high thermal conductivity, Sr substitution by a higher-valence heavy element could improve its thermoelectric performance. The optimum carrier concentration is crucial in the design of doped STO with high performance. This study aims to determine the effects of Lanthanum doping on the crystal and electronic structure of STO and models its thermoelectric properties using single parabolic band model. La\(_{x}\)Sr\(_{1-1.5x}\)TiO\(_3\) (x = 0, 0.05, 0.1, and 0.15) samples were successfully synthesized using solid-state method. The reduction of the lattice parameter confirmed Lanthanum doping to STO. Diffuse Reflectance Spectroscopy measurements show a slight variation of band gap of La\(_{x}\)Sr\(_{1-1.5x}\)TiO\(_3\) relative to STO. The modelling with single parabolic band model was performed and revealed the carrier concentration for optimum power factor and the electronic contribution to the thermal conductivity.
Keywords: Thermoelectric, La-doping, SrTiO\(_3\), single parabolic band model, power factor
