Phonon Engineering for Thermoelectric Enhancement of p-Type Bismuth Telluride by a Hot-Pressing Texture Method

Abstract

Phonon engineering is a core stratagem to improve the thermoelectric performance, and multi-scale defects are expected to scatter a broad range of phonons and compress the lattice thermal conductivity. Here, we demonstrate obviously enhanced thermoelectric properties in Bi0.48Sb1.52Te3 alloy by a hot-pressing texture method along the axial direction of a zone-melted ingot. It is found that a plastic deformation of grain refinement and rearrangement occurs during the textured pressing process. Although the obtained power factor is slightly decreased, a large amount of grain boundaries emerges in the textured samples and dense dislocations are observed around the boundaries and inside the grains. These additional phonon scattering centers can effectively scatter the low- and mid-frequency phonons, and the corresponding lattice thermal conductivity is significantly reduced to only 50% of that of zone-melted samples. Consequently, the maximum figure of merit (ZT) reaches 1.44 at 330 K and the average ZT (300–380 K) reaches 1.38. This study suggests that the simple hot-pressing texture technique is a promising method to significantly optimize the cooling capacity of Bi0.48Sb1.52Te3-based thermoelectric refrigeration.

Organic/Inorganic Hybrid Design as a Route for Promoting the Bi0.5Sb1.5Te3 for High‐Performance Thermoelectric Power Generation

“…[32,33] The rich heterogeneous interfaces in these composites are very effective for phonon scattering. [34][35][36][37][38] For example, a high average zT avg ≈1.08 between 300 and 523 K was achieved in 0.5 vol.% graphene/Bi 0.5 Sb 1.5 Te 3 (BST), due to the significantly decreased κ. [39] Furthermore, copper-containing compounds, for example, CuO [40] and CuTe [41] nano-materials have been proven effective to improve the TE performance of Bi 2 Te 3 -based materials.…”

Enhanced Thermoelectric and Mechanical Performances in Sintered Bi0.48Sb1.52Te3–AgSbSe2 Composite

“…However, only the Bi 2 Te 3 -based materials have been commercially applied near room temperature. The commercial applications of both power generation and refrigeration are mainly based on zone-melted (ZM) Bi 2 Te 3 materials, which seriously suffer from mediocre TE properties and poor mechanical performance. − To meet the growing demand of applications, many efforts have been made to develop Bi 2 Te 3 sintered materials synthesized by hot pressing (HP), spark plasma sintering (SPS), and some derived approaches such as melt spinning (MS), , hot deformation (HD), − high-energy ball milling (BM), , and liquid-phase sintering (LPS). , Various sintering methods not only enhance the mechanical performance, but also introduce lattice distortion, dislocations, and nanograins to strengthen the phonon scattering and decrease κ l , resulting in a synergistic optimization of mechanical and TE properties for Bi 2– x Sb x Te 3– y Se y materials. Recently, the addition of a second-phase during the sintering process, a more direct scheme to introduce scattering centers into the matrix, has been widely applied into synchronously optimizing the phononic and electronic transport coefficients of the Bi 2 Te 3 -based composite systems. − Inspired by these aforementioned works, researchers keep exploring new composite systems to synthetically elevate the property of Bi 2– x Sb x Te 3– y Se y sintering materials.…”

Current State‐of‐the‐Art in the Interface/Surface Modification of Thermoelectric Materials

“…In recent decades, numerous strategies were applied to investigate the rational design and development of TE materials. The main concepts for optimizing the zT value converge toward two approaches: i) enhancing the PF in terms of electrical properties by point‐defect engineering, [ 9–11 ] band engineering, [ 12–14 ] texturing, [ 15–17 ] and energy filtering; [ 18–20 ] ii) decreasing the independent lattice thermal conductivity via nanostructuring, [ 21–23 ] phonon engineering, [ 24–26 ] interfacial modifications, [ 27–29 ] or searching for new TE materials with intrinsically low thermal conductivity. [ 30–32 ]…”