Enhancement of Thermoelectric Performance in Bi 0.5 Sb 1.5 Te 3 Particulate Composites Including Ferroelectric BaTiO 3 Nanodots.

An increasing number of studies have reported producing composite structures by combining thermoelectric and functional materials. However, combining energy filtering and ferroelectric polarization to enhance the dimensionless figure of merit thermoelectric ZT remains elusive. Here we report a composite that contains nanostructured BaTiO 3 embedded in a Bi 0.5 Sb 1.5 Te 3 matrix. We show that ferroelectric BaTiO 3 particles are evenly composited with Bi 0.5 Sb 1.5 Te 3 grains reducing the concentration of free charge carriers with increasing BaTiO 3 content. Additionally, as a result of the energy-filtering effect and ferroelectric polarization, the Seebeck coefficient was improved by ∼10% with a ∼10% improvement in power factors. The BaTiO 3 phase can effectively scatters phonons reducing lattice thermal conductivity κ l (0.5 W m -1 K -1 ) and increasing ZT to 1.31 at 363 K in Bi 0.5 Sb 1.5 Te 3 composites with 2 vol % BaTiO 3 content giving an improvement of ∼25% over pure Bi 0.5 Sb 1.5 Te 3 . Our work indicates that the introduction of ferroelectric nanoparticles is an effective method for optimizing the ZT of Bi 0.5 Sb 1.5 Te 3 -based thermoelectric materials.