Thermoelectric performance of CuFeS2+2x composites prepared by rapid thermal explosion

Abstract

Although many thermoelectric materials, such as Bi 2 Te 3 , PbTe and CoSb 3 , possess excellent thermoelectric properties, they often contain toxic and expensive elements. Moreover, most of them are synthesized by processes such as vacuum melting, mechanical alloying or solid-state reactions, which are highly energy and time intensive. All these factors limit commercial applications of the thermoelectric materials. Therefore, it is imperative to develop efficient, inexpensive and non-toxic materials and explore rapid and low-cost synthesis methods. Herein we demonstrated a rapid, facile and low-cost synthesis route that combines thermal explosion (TE) with plasma-activated sintering and used it to prepare environmentally benign CuFeS 2+2x . The phase transformation that occurred during the TE and correlations between the microstructure and transport properties were investigated. In a TE process, single-phase CuFeS 2 was obtained in a short time and the thermoelectric performance of the bulk samples was better than that of the samples that were synthesized using traditional methods. Furthermore, the effect of phase boundaries on the transport properties was investigated and the underlying physical mechanisms that led to an improvement in the thermoelectric performance were revealed. This work provides several new ideas regarding the TE process and its utilization in the synthesis of thermoelectric materials. INTRODUCTIONIn the past few decades, increased concerns regarding environmental degradation and rising energy costs have sparked vigorous research activities to identify alternative energy sources and develop novel energy materials. One of the most exciting clean energy conversion technologies is thermoelectricity that can be used to harvest waste industrial heat via the Seebeck effect and convert it into electricity using a purely solid-state means without moving parts [1][2][3][4][5] . The efficiency of the conversion process is determined by the dimensionless figure of merit ZT = α 2 σT /(κ e +κ L ), where α is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ e and κ L are the electronic and lattice contributions, respectively, to the thermal conductivity 6-11 . Basically, a good thermoelectric material should have both a high Seebeck coefficient and electrical conductivity, and possess as low a thermal conductivity as possible. [27][28][29] . Although they all possess a highenergy conversion efficiency, most of them contain toxic and expensive elements. Moreover, the synthesis processes that are used consume considerable energy and are time intensive. The above limitations constrain their large-scale industrial applications. Thus, it is important to develop efficient, inexpensive and environmentally

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

“…Figure 7f shows ZT as a function of T , in which ZT reaches up to 0.22 at 653 K for this pristine CuFeSe 2 nanomaterial, which is among the largest values obtained for a tellurium-free material comparable with doped CuFeX 2 (X = S, Se) materials in this similar temperature range (Figure 8) [33,48,49,50,51,52,53], with the additional advantage of low-cost associated with solution processing strategies. Most importantly, the mid-temperature ZT has been significantly increased caused by the higher power factor ( PF ) and simultaneously reduced thermal conductivity ( κ total ) over a wide temperature range.…”

Structural and Thermoelectric Properties of Solid–Liquid In4Se3-In Composite

“…The similar mechanism has been proposed for the explanation of thermal conductivity behaviour. 54,55 It could be explained by two reasons: phonon scattering at phase boundaries of the metal In-semiconductor In 4 Se 3 composition in solid-solid or solid-liquid state, and the second reason could be the result of the phonons scattering at point defects: In i and V Se .…”

“…The low thermal conductivity of these samples should be attributed by the phonon scattering at interlayers of their two-dimensional In/Se quasi-layers structures of In 4 Se 3 phase, which is regularly found in natural 2D layer structures, for instance, SnSe 47 or LnO-CuSe (Ln = La, Bi). [48][49][50] This low thermal conductivity might also result from phonon scattering at the phase boundary in composites, 51,52 from the point defects (In i , V Se ) in the In 3 Se 4 , or other defects. 6,17,18 On the other hand, the additional effect of liquid-solid interphase at high temperature on the scattering of medium and high frequent phonons could also contribute to the low thermal conductivity of this composite.…”

Realization of non-equilibrium process for high thermoelectric performance Sb-doped GeTe

“…In Bi 2 Te 3 doped (GeTe) 0.95 (Bi 2 Te 3 ) 0.05 [35] , enhanced thermoelectric properties were achieved by optimizing the powder ball milling processing parameters resulting in sub-micro features which reduce the lattice thermal conductivity leading to enhanced ZT value of $1.6. Beyond that, various novel synthesis techniques were devoted to enhance the performance of thermoelectric materials [13,[36][37][38][39][40][41][42][43][44]. Recently, melt spinning (MS) has been proposed as an ultra-fast novel synthesis technique for the fabrication of TE materials with microstructures and TE properties unattainable through other fabrication processes [45][46][47][48][49][50][51][52].…”