Synergistic Optimization of the Thermoelectric and Mechanical Properties of Large-Size Homogeneous Bi_0.5Sb_1.5Te₃ Bulk Samples via Carrier Engineering for Efficient Energy Harvesting

Abstract

Manufacturing an economically viable, efficient commercial thermoelectric (TE) module is essential for power generation and refrigeration. However, mediocre TE properties, lack of good mechanical stability of the material, and significant difficulties involved in the manufacturing of large-scale powder as well as bulk samples hinder the potential applications of the modules. Herein, an economically feasible single-step water atomization (WA) is employed to synthesize BST powder (2 kg) by Cu doping within a short time and consolidated into large-scale bulk samples (500 g) for the first time with a diameter of 50 mm and a thickness of about 40 mm using spark plasma sintering (SPS). The incorporation of Cu into BST greatly boosts the carrier concentration, leading to a significant increase in electrical conductivity, and inhibits the bipolar thermal conductivity by 73%. Synchronously, the lattice contribution (κL) is greatly reduced by the effective scattering of phonons by comprising fine-grain boundaries and point defects. Therefore, the peak ZT is shifted to the mid-temperature range and obtained a maximum of ∼1.31 at 425 K and a ZT ave of 1.24 from 300 to 500 K for the BSTCu0.05 sample, which are considerably greater than those of the bare BST sample. Moreover, the maximum compressive mechanical strength of large-size samples manufactured by the WA-SPS process is measured as 102 MPa, which is significantly higher than commercial zone melting samples. The thermoelectric module assembled with WA-SPS-synthesized BSTCu0.05 and commercial n-type BTS material manifests an outstanding cooling performance (−19.4 °C), and a maximum output power of 6.91 W is generated at ΔT ∼ 200 K. These results prove that the BSTCu x samples are eminently suitable for the fabrication of industrial thermoelectric modules.

Improved Thermoelectric Performance of Sb2Te3 Nanosheets by Coating Pt Particles in Wide Medium-Temperature Zone

“…In order to assess the uniformity, element mapping of Sb and Te was performed using Energy-Dispersive X-ray Spectroscopy (EDS), as shown in Figure 2b,c, confirming the good homogeneity of the material. Based on the Mott formula [47][48][49][50] for a degenerated semiconductor, the Seebeck coefficient could be written as follows:…”

“…Moreover, element mapping of Pt within the same region confirmed the uniform coating of Pt particles on the surface of the hexagonal sheets, as illustrated in Figure 3e and Table 1. Based on the Mott formula [47][48][49][50] for a degenerated semiconductor, the Seebeck coefficient could be written as follows: The microstructural analysis conducted using FE-SEM and HRTEM provided valuable insights into the morphology and composition of Sb 2 Te 3 coated with Pt nanoparticles. The observations confirmed the regular hexagonal sheet structure of Sb 2 Te 3 and demonstrated the uniformity of the material.…”

“…Based on the Mott formula [47][48][49][50] for a degenerated semiconductor, the Seebeck coefficient could be written as follows:…”

Realizing High Thermoelectric Performance in Bi0.4Sb1.6Te3 Nanosheets by Doping Sn Element

“…For Sn x BST ( x = 0, 0.04, 0.06) TE ingots, the absolute S value gradually increases and then decreases. To figure out the reason for this phenomenon, when electrons or holes are dominant, under the single parabolic band (SPB) model assumption, − the Seebeck coefficient and carrier concentration could be expressed as follows: where F n (η) is the n th Fermi integral, and m *, r , k B , e , T , and η are the effective mass, scattering factor, Boltzmann constant, electron charge, absolute temperature, and reduced Fermi energy (defined as η = ). When acoustic phonon scattering is dominant, r = −1/2.…”

Enhancing Thermoelectric and Mechanical Properties of p-Type (Bi, Sb)2Te3 through Rickardite Mineral (Cu2.9Te2) Incorporation

“…The lattice parameter calculations indicate a slight decrease in the a value and a marginal increase in the c value for both BST-5 and BST-3 samples upon doping with Cu 2.9 Te 2 , as shown in Figure S1. Previous studies have observed that in the crystal structure of BST, Cu can either substitute on the Bi/Sb site, 5,42,44,47,52,53 or be intercalated in the van der Waals gaps located between quintuple layers. 54 If Cu is intercalated, then the c parameter should increase with the increase in Cu content.…”