Enhancement of Thermoelectric Performance in Bi_0.5Sb_1.5Te₃ Particulate Composites Including Ferroelectric BaTiO₃ Nanodots

Abstract

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 BaTiO3 embedded in a Bi0.5Sb1.5Te3 matrix. We show that ferroelectric BaTiO3 particles are evenly composited with Bi0.5Sb1.5Te3 grains reducing the concentration of free charge carriers with increasing BaTiO3 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 BaTiO3 phase can effectively scatters phonons reducing lattice thermal conductivity κl (0.5 W m–1 K–1) and increasing ZT to 1.31 at 363 K in Bi0.5Sb1.5Te3 composites with 2 vol % BaTiO3 content giving an improvement of ∼25% over pure Bi0.5Sb1.5Te3. Our work indicates that the introduction of ferroelectric nanoparticles is an effective method for optimizing the ZT of Bi0.5Sb1.5Te3-based thermoelectric materials.

Engineering of Thermoelectric Composites Based on Silver Selenide in Aqueous Solution and Ambient Temperature

“…The lower κ tot measured for the composites is associated with a more effective scattering of phonons at point defects created by Bi 3+ and extensive interphases between Ag 2 Se and Bi 2 S 3 in the case of the highest doped samples. Numerous previous works have reported a decrease of thermal conductivity with a minor effect on electrical conductivity and have associated this phenomenon with different explanations, including a strong scattering on phonons created by precipitates without strongly affecting electrical conductivity, hierarchical architecture with multiscale defects differently affecting phonons and electrons, phonon scattering by introduced electrically dopant atoms, and preferential phonon scattering by introduced nanoparticles …”

“…Numerous previous works have reported a decrease of thermal conductivity with a minor effect on electrical conductivity and have associated this phenomenon with different explanations, including a strong scattering on phonons created by precipitates without strongly affecting electrical conductivity, 63 hierarchical architecture with multiscale defects differently affecting phonons and electrons, 60 phonon scattering by introduced electrically dopant atoms, 64 and preferential phonon scattering by introduced nanoparticles. 65 The temperature dependence of the TE figure or merit, zT, is displayed in Figure 6a. For the pristine Ag 2 Se pellet, the zT value increases from 0.62 at 300 K to 0.76 at 380 K. The zT values of the Ag 2 Se-x wt % Bi 2 S 3 composites increase with the introduction of 0.5−1.0 wt % Bi 2 S 3 .…”

Enhanced Thermoelectric Performance of NixBi0.5Sb1.5Te3via In Situ Formation of NiTe2 Channels

“…This enhancement in ZT is attributed to high electrical conductivity and Seebeck coefficient of Ni 0.04 Bi 0.5 Sb 1.5 Te 3 due to channel formation of NiTe 2 within the matrix of BST. Further, we also compared our ZT value with recently reported ZT of BiSbTe-based materials (refs –), which are appended in Table .…”

A new thermoelectric Ag8SiSe6 argyrodite for room temperature application: sensitivity of thermoelectric performance to cooling conditions

“…3 In recent years, several strategies, including modulation doping, inducing resonant levels, and band convergence, have been adopted to obtain higher electrical properties and power factors for relevant materials. These enhancements have been verified in SnSe, 4 PbTe, [5][6][7] Bi 2 Te 3 , 8 and BiCuSeO. 9 To optimize the thermal conductivity, strategies such as the incorporation of nano-inclusions, secondary phase recombination, and lattice anharmonicity have been introduced, and have been successfully applied to reduce the thermal conductivity of thermoelectric materials such as Bi 2 Te 3 , 10 CoSb 3 , 11 Cu 3 SbSe 4 , 12 AgSbTe 2 , 13 SnTe, 14 and Ag 8 SnSe 6 .…”