Thermoelectric properties of La-doped A-site SrTiO₃ ceramics synthesised by the sol-gel auto-combustion technique

ABSTRACT

Sr_(1–x)La_xTiO₃ (SLTO) nanopowder (x = 0, 0.01, 0.05, 0.07, and 0.10) were effectively synthesised by the sol-gel auto-combustion process. Bulk ceramics samples were produced by spark plasma sintering (SPS) in an Ar atmosphere. The XRD pattern of the undoped SLTO nanopowder showed the pure phase and the impurity phase (TiO₂) was detected in the La-doped SLTO samples. However, the impurity phase disappeared after producing the bulk samples with the SPS process. All the samples exhibited a negative Seebeck coefficient (S). The electrical conductivity (σ) and negative Sof all the SLTO samples increased with increasing temperature and reached a maximum value at 800 K. The thermal conductivity (κ) decreased with increasing temperature and increasing La content. The SLTO with x = 0.01 showed the largest σ, negative S, power factor (S²σ) and dimensionless figure of merit (ZT) at 800 K.

KEYWORDS:

• Oxide thermoelectric materials
• Electrical property
• Seebeck coefficient
• Thermal property
• Thermoelectricity

Acknowledgments

We would like to thank The National Science, Research and Innovation Fund (NSRF) through Naresuan University (R2565B028) and Thailand Science Research and Innovation (TSRI) through the Royal Golden Jubilee PhD. Program (PHD/0049/2560), which provided the budget. Many thanks also to the Institute for Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Nonthaburi and Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan for providing a facility for our thermoelectric measurements. We also wish to thank Mr Roy I. Morien of the Naresuan University Graduate School for his assistance in editing the grammar, syntax and English expression in this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).