Synthesis and thermoelectric performance of titanium diboride and its composites with lead selenide and carbon

Abstract The exploration of new thermoelectric material is the current area of research in energy conversion and storage technologies, in that nanocomposite approach is a promising root to get desirable thermoelectric properties. The present study demonstrates a composite containing highly conductive titanium diboride (TiB2), polyvinyl alcohol (PVA) as binder and lead selenide (PbSe) as semiconductor. The synthesis and transport physics are studied with an intention to increase the power factor and figure of merit (ZT) of TiB2 by reducing thermal conductivity through creating inhomogeneity in microstructures. Sol gel method and carbothermal reduction reaction have been used to synthesize TiB2. More than 95% of thermal conductivity is reduced due to the phonon scattering, which is desirable to achieve a high power factor and ZT. TiB2/PVA composite possesses a very low Seebeck coefficient and exhibits three order of magnitude reduction in electrical conductivity, which hinders in achieving a good power factor and ZT. Power factor of 25.3 µW/mK2, Seebeck coefficient of 36.3 μV/K at 550 K and electrical conductivity of 2.5 × 104 S/m at ~300 K and ZT of 0.064 at 550 K are worth to report in this study. Finally, the synthesized TiB2 is incorporated into PbSe to evaluate thermoelectric properties. Maximum ZT of 0.12 at 495 K, Seebeck coefficient of −342 µV/K at 550 K, electrical conductivity of 2.8 × 103 S/m at 400 K, thermal conductivity of 1.03 W/mK at 550 K and highest power factor of 280.2 µW/mK2 at 495 K have been achieved in this composite.