Effect of spark plasma sintering (SPS) on the thermoelectric properties of magnesium ferrite

Abstract

Magnesium ferrite MgFe 2 O 4 was synthesized with two different methods, spark plasma sintering (SPS) and conventional solid-state reaction sintering (SSRS), and thermoelectric properties were investigated. SPS processing was found to yield two attractive features: SPS at 900°C enabled retaining the submicron particle size of 0.3-0.5 lm from ball-milling, leading to lower thermal conductivity, 3 W/mK@300 K. 1200°C SPS sintering led to the same sample grain size of 1.0-3.0 lm as SSRS, but still exhibited significantly lower thermal conductivity of 4.3 W/mK@300 K compared to the SSRS sample with 14 W/mK@300 K, which exhibited neck formation between particles. Furthermore, while the finer microstructuring led to a reduction in the thermal conductivity, the resistivity of SPS MgFe 2 O 4 showed little dependence on the particle size at expected thermoelectric working temperatures above 523 K, which indicates success to some degree of phonon selective scattering due to differences in mean-free-paths of electrons and phonons. As a process, SPS samples are found to exhibit four-to sevenfold enhancement of ZT compared to the conventional SSRS sample. While the maximum ZT in the present samples is relatively low, taking a value of 0.07 for the SPS 1200°C sintered sample, the processing insights may be utilized for similar systems.

Progress of Spark Plasma Sintering (SPS) Method, Systems, Ceramics Applications and Industrialization

“…To comply with the SPS size effect and shape effect, it requires enlargement management know-how to attain dense and homogeneous SPS sintered materials. Although SPS research and development on other categories of materials both of ceramics and metals were not discussed in this paper, such as transparent ceramics [75][76][77][78], MMC/FRC/FRM [79][80][81][82], CNT/CNF various composite materials [83][84][85][86][87][88][89][90][91][92][93], thermo-electric semiconductors of SiGe, Bi 2 Te 3 , FeSi 2 , CoSb 3 , MnSi 2, Mg 2 Si, MgFe 2 O 4 systems for clean energy generation [94][95][96][97][98], nuclear materials [99], Nd-Fe-B, Sm 2 Co 17 and ferrite for magnetic materials [100,101], MgB 2 superconducting materials [102], PbTiO 3 dielectric materials [103], lithium battery [104], shape memory alloys, solid cell materials, glassy metals, and optically functional materials, nevertheless, they are promising candidates for industrial SPS applications. Ceramicceramic solid-phase SPS bonding processing is also attractive for industries.…”

High-Performance Thermoelectric Oxides Based on Spinel Structure

“…[25][26][27][28][29][30] Subsequently, through computational survey into uncharted materials' territory, one may find a desirable oxide alternative to the common thermoelectric materials, at least for those applications where exposure to elements is inevitable. More specifically, our study was motivated by the recent prediction, 31 and observation 32 of spinel oxides with high Seebeck coefficient, and high-performance thermoelectric cubic oxides. 33 Therefore, in this work, we surveyed a specific class of spinel ferrites, isomorphic to magnetite, in search of high S. In particular, our survey spanned twelve 3d and 4d transition metal (TM) containing spinel ferrites, where the TM ions are tetrahedrally coordinated by O, A site, while the Fe ions are octahedrally coordinated, B site (Figure 1).…”

“…Computational screening has recently emerged as a novel tool in the discovery of brand-new thermoelectric materials. − Subsequently, through computational survey into uncharted materials’ territory, one may find a desirable oxide alternative to the common thermoelectric materials, at least for those applications where exposure to elements is inevitable. More specifically, our study was motivated by the recent prediction and observation of spinel oxides with high Seebeck coefficient and high-performance thermoelectric cubic oxides . Therefore, in this work, we surveyed a specific class of spinel ferrites, isomorphic to magnetite, in search of high S .…”

Enhanced mechanism of thermoelectric performance of Bi2Se3 using density functional theory

“…Thermoelectricity has become fascinating prospect for use in generating green energy especially from the processes of waste heat [1][2][3]. The narrow-band gap (0.3 eV) semiconductor such as Bi 2 Se 3 has been recognized as an outstanding thermoelectric material [4][5][6].…”