Development of High-Performance Thermoelectric Materials by Microstructure Control of P-Type BiSbTe Based Alloys Fabricated by Water Atomization

Abstract

Developing inexpensive and rapid fabrication methods for high efficiency thermoelectric alloys is a crucial challenge for the thermoelectric industry, especially for energy conversion applications. Here, we fabricated large amounts of p-type Cu0.07Bi0.5Sb1.5Te3 alloys, using water atomization to control its microstructure and improve thermoelectric performance by optimizing its initial powder size. All the water atomized powders were sieved with different aperture sizes, of 32–75 μm, 75–125 μm, 125–200 μm, and <200 μm, and subsequently consolidated using hot pressing at 490 °C. The grain sizes were found to increase with increasing powder particle size, which also increased carrier mobility due to improved carrier transport. The maximum electrical conductivity of 1457.33 Ω−1 cm−1 was obtained for the 125–200 μm samples due to their large grain sizes and subsequent high mobility. The Seebeck coefficient slightly increased with decreasing particle size due to scattering of carriers at fine grain boundaries. The higher power factor values of 4.20, 4.22 × 10−3 W/mk2 were, respectively, obtained for large powder specimens, such as 125–200 μm and 75–125 μm, due to their higher electrical conductivity. In addition, thermal conductivity increased with increasing particle size due to the improvement in carriers and phonons transport. The 75–125 μm powder specimen exhibited a relatively high thermoelectric figure of merit, ZT of 1.257 due to this higher electric conductivity.

Additive Manufacturing of Thermoelectrics: Emerging Trends and Outlook

“…These layers severely decrease the charge carrier mobility values. 135 In addition, well-controlled heating ramp rates and temperature will minimize sudden polymer outgassing which may lead to crack formation. However, He and colleagues leveraged on the incomplete thermal decomposition of the polymer to form amorphous carbon as shown in Figure 7d.…”

“…An increase in grain size will allow an increase in carrier mobility across grains, leading to higher electrical conductivity but a reduction in Seebeck coefficient. 135 The increase in grain size would also cause an increase in thermal conductivity due to increased phonon transport. As such, characterization and optimization heat treatment studies have to be conducted to minimize effects of the trade-offs between the increases in both electrical conductivity and thermal conductivity and the decrease in Seebeck coefficient on zT values.…”

“…A low flow rate during polymer outgassing will result in oxidative and carbonaceous layers to form around the inorganic TE surface. These layers severely decrease the charge carrier mobility values . In addition, well-controlled heating ramp rates and temperature will minimize sudden polymer outgassing which may lead to crack formation.…”

“…Figure a illustrates the possibilities of optimizing the grain size through the sintering temperature and dwelling period. An increase in grain size will allow an increase in carrier mobility across grains, leading to higher electrical conductivity but a reduction in Seebeck coefficient . The increase in grain size would also cause an increase in thermal conductivity due to increased phonon transport.…”

The Effect of Reactive Electric Field-Assisted Sintering of MoS2/Bi2Te3 Heterostructure on the Phase Integrity of Bi2Te3 Matrix and the Thermoelectric Properties

“…In order to develop high-performance TE materials, several efficient concepts have been employed, such as nano structuring [ 4 , 5 , 6 ], doping [ 7 , 8 ], solid solutions [ 9 ], energy filtering [ 10 ], band convergence [ 11 ], and magnetic enhancement [ 12 , 13 ]. Recently, developing composites for tuning the TE characteristics materials appear promising and constitute a striking strategy to improve the performance of TE materials [ 14 , 15 , 16 , 17 , 18 ].…”