Lattice Thermal Conductivity Reduction Due to In Situ-Generated Nano-Phase in Bi0.4Sb1.6Te3 Alloys by Microwave-Activated Hot Pressing

Abstract

The p-type Bi 0.4 Sb 1.6 Te 3 alloys are prepared using a new method of mechanical alloying followed by microwave-activated hot pressing (MAHP). The effect of sintering temperature on the microstructure and thermoelectric properties of Bi 0.4 Sb 1.6 Te 3 alloys is investigated. Compared with other sintering techniques, the MAHP process can be used to produce relatively compact bulk materials at lower sintering temperatures owing to its unique sintering mechanism. The grain size of the MAHP specimens increases gradually with the sintering temperature and a partially oriented lamellar structure can be formed in some regions of specimens obtained. The formation of the in situgenerated nano-phase is induced by the arcing effect of the MAHP process, which enhances the phonon scattering effect and decreases the lattice thermal conductivity. A minimum lattice thermal conductivity of 0.41 W/(mAEK) and a maximum figure of merit value of 1.04 are obtained at 100°C for the MAHP specimen sintered at 325°C. This technique may also be extended to other functional materials to obtain ultrafine microstructures at low sintering temperatures.

Microstructure tailoring in nanostructured thermoelectric materials

“…The microwave energy was simultaneously applied on the pre-sintered powders under an axial mechanical load. As a result, high density of the nanostructured BiSbTe samples can be realized at lower temperature, and minimum lattice thermal conductivity of 0.41 W/(m Á K) and a maximum ZT value of 1.04 are obtained at 325 C. 79 …”

Enhancement of Diffusion, Densification and Solid-State Reactions in Dielectric Materials Due to Interfacial Interaction of Microwave Radiation: Theory and Experiment

“…The samples prepared using the MW method had a lower thermal conductivity compared to a conventionally prepared sample, which contributed to a higher zT value. In another experiment, Fan et al 53 developed p-type Bi 0.4 Sb 1.6 Te 3 alloys by mechanical alloying followed by MW-activated hot pressing (MAHP). The results showed an enhancement in the phonon scattering and the reduction of the lattice thermal conductivity as low as 0.41 W/mK at 100 °C.…”

Oxidation Protective Hybrid Coating for Thermoelectric Materials

“…A considerable effort has been made to produce materials with high figure of merit, and several compounds have been identified and improved using different approaches: doping elements; composites; nanostructuring; and mesostructuring [ 3 , 4 , 8 ]. The effect of conventional synthesis and sintering techniques have been evaluated [ 9 ] and innovative methods are constantly under development [ 10 , 11 , 12 , 13 , 14 ]. One of the main challenges in the thermoelectrics field is the identification of efficient materials that are inexpensive, easy to be produced, and formed of earth-abundant and environmentally friendly elements.…”