Synergistically Optimized Thermoelectric Performance in Bi_0.48Sb_1.52Te₃ by Hot Deformation and Cu Doping

Abstract

In recent decades, bismuth telluride (Bi2Te3) has been in widespread use for normal-temperature thermoelectric cooling. However, commercial zone-melted bismuth telluride faces the big challenge of dramatically decreased thermoelectric properties at higher temperature, which limits its usage at intermediate temperature. In this contribution, the thermoelectric performance of p-type bismuth telluride is enhanced via a synergistic optimization by hot deformation and copper doping. Hot deformation treatment boosts the grain growth and exhibits donor-like effects, leading to improved electronic transport properties. Meanwhile, high-density dislocations and lattice distortions induced by dynamic recrystallization aggravate the phonon-related scattering and significantly compress the lattice thermal conductivity. In addition, copper doping effectively tunes the hole concentration, and the generated point defects also reduce the lattice thermal conductivity. Consequently, a high ZT max of 1.1 at 400 K and ZT ave of 1.0 between 300–500 K were obtained in hot-deformed Cu0.01Bi0.48Sb1.52Te3. This study suggests that the synergistic effect of hot deformation and copper doping is promising to boost the near-normal-temperature thermoelectric power generation of Bi2Te3-based thermoelectrics.

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

“…[53][54][55][56][57][58] Despite many studies having found equations given by λ 2 ¼ constant (V ) À2/3 for different alloy systems, [59][60][61][62] the effects of lateral solute segregation on the wavelengths of instabilities along the sides of primary dendritic stems for Bi-based alloys are still not well understood. Herein, a single power law in which the exponent À1.1 characterizes the experimental evolution of λ 2 as a function of V L for all Bi- (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) wt% Sb alloys is proposed. Figure 10 shows Vickers microhardness (HV) for the analyzed Bi-Sb alloys as a function of Sb concentration along the length of DS castings, highlighting the solidification microstructure morphologies.…”

“…Particularly, Bi-based alloys are highlighted as potential Pb-free alloys for the replacement of the conventional Sn-Pb solder TIMs used in electronic assemblies. [12] As a matter of fact, Bi-based alloys are also suggested for various applications as thermoelectric materials, [13][14][15] optical and electro-optical devices, [16] hall sensors, [17] and lubricant materials. [18] However, the great challenge in developing new Bi alloys is the enhancement of a specific property without compromising other important physical properties, as stated by Septimio et al [19] From this perspective, controlling the microstructure through solidification thermal parameters is of critical importance because it plays an important role on the resulting properties of metallic alloys.…”

“…Despite Bi-based alloys having exhibited promising potential as TIMs in microelectronics cooling applications, understanding the microstructure evolution of these alloys and the consequent effects on the resulting properties still remains an essential task to be accomplished. Herein, a directional solidification technique is used to investigate microstructural features and Vickers microhardness of Bi (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) wt% Sb alloys with a focus on the roles of alloy composition, solidification thermal parameters, and macrosegregation. The results show the formation of aligned Bi-rich dendrites in a broad range of cooling rates from about 0.2 to 25 C s À1 .…”

Recent advances, design guidelines, and prospects of flexible organic/inorganic thermoelectric composites

“…47 Recently, hot pressing has become a relatively mature technique for the preparation of thermoelectric nanocomposites. 38,[48][49][50] Because of the thermoplasticity of the polymer matrix, most dense organic-inorganic composites can be fabricated via a simple homemade hot pressing device. J. Kim et al 51 prepared n-type carbon bucky paper with carbon nanotubes and a PVDF composite via hot pressing at 60 1C in 6 MPa for 3 min.…”

Boosted carrier mobility and enhanced thermoelectric properties of polycrystalline Na0.03Sn0.97Se by liquid-phase hot deformation

“…44 Obviously, both LPS and HD processes contribute to texture modulation and result in better electronic properties as well as mechanical properties in SnSe-based materials. Nevertheless, the HD procedure is somewhat complicated and energy-consuming with poor repeatability, [44][45][46][47][48] while the LPS process may induce a higher thermal conductivity. 43,[49][50][51] Recently, the liquid-phase hot deformation (LPHD) technique was proposed in n-type Bi 2 (Te,Se) 3 alloys.…”