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

Babu Madavali,Jong-Soo Rhyee,Pathan Sharief,Gian Song,Kyoung-Tae Park,Song-Yi Back,Soon-Jik Hong

doi:10.3390/ma14174870

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.

Highlights

Thermoelectric renewable energy devices can operate in two directions, in power generation mode and thermoelectric cooling mode
We have mainly focused on the effect of different water atomized (WA) particle sizes on microstructural features, and their subsequent effect on thermoelectric properties and mechanical properties were systematically investigated
The rapid cooling rate due to the water stream during the atomization process was responsible for the formation of the irregular shapes, unlike the spherical powders produced by gas atomizer

Summary

Introduction

Thermoelectric renewable energy devices can operate in two directions, in power generation mode and thermoelectric cooling mode. The power generation mode is based on the Seebeck effect, where a temperature gradient between two different materials can develop a voltage. Thermoelectric cooling is based on the Peltier effect, where cooling and heat can be generated at the junctions of two different materials by maintaining an electrical current [1,2,3]. The quality of a thermoelectric device is evaluated using the dimensionless figure of merit, ZT = σα T/κ, where σ is electrical conductivity in 1/Ωcm, α is the Seebeck coefficient in μV/K, T is the working temperature in K, and κ is thermal conductivity in W/m-K [4,5,6]. Seebeck coefficient and low thermal conductivity, such as ceramics/glass materials, and simultaneously exhibit high electrical conductivity, such as single crystals, can exhibit high 4.0/). Many researchers have developed various thermoelectric materials, including Bi-Te based alloys [7,8], Pb-Te based alloys [9], clathrates (Ba-Cu-Si) [10], skutterudites (Co4 Sb12 ) [11], Ag-Pb based alloys [12], and half Heusler [13] in efforts to enhance thermoelectric performance

Methods

Results

Conclusion