Ioffe–Regel limit and lattice thermal conductivity reduction of high performance (AgSbTe2)15(GeTe)85 thermoelectric materials

Zhu, Tiejun; Gao, Hongli; Chen, Yi; Zhao, Xinbing

doi:10.1039/c3ta15147f

Cited by 66 publications

(74 citation statements)

References 20 publications

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“…The electronic thermal conductivity κ e was calculated for sample 1 from the data in Figure 6a,b using the Wiedemann–Franz law κ e /σ = LT , where the Lorenz number as a function of temperature was obtained from the relationship L = 1.5 + exp(−| S |/116) as proposed by Kim et al for nondegenerate semiconductors 38 (Supporting Information, Figure S5). The data plotted in Figure 6d imply that the lattice thermal conductivity κ l is in the range 0.7–1.0 W m –1 K –1 , in agreement with that reported by Zhu et al 17 It is noticeable that κ total is slightly lower on initial heating, despite σ being higher. This implies a significant increase in κ l after the first heating cycle, which is likely due to a change in domain structure and requires further investigation.…”

Section: Resultssupporting

confidence: 89%

Phase Transitions of Thermoelectric TAGS-85

et al. 2017

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The alloys (GeTe)x(AgSbTe2)100–x, commonly known as TAGS-x, are among the best performing p-type thermoelectric materials for the composition range 80 ≤ x ≤ 90 and in the temperature range 200–500 °C. They adopt a rhombohedrally distorted rocksalt structure at room temperature and are reported to undergo a reversible phase transition to a cubic structure at ∼250 °C. However, we show that, for the optimal x = 85 composition (TAGS-85), both the structural and thermoelectric properties are highly sensitive to the initial synthesis method employed. Single-phase rhombohedral samples exhibit the best thermoelectric properties but can only be obtained after an annealing step at 600 °C during initial cooling from the melt. Under faster cooling conditions, the samples obtained are inhomogeneous, containing multiple rhombohedral phases with a range of lattice parameters and exhibiting inferior thermoelectric properties. We also find that when the room-temperature rhombohedral phase is heated, an intermediate trigonal structure containing ordered cation vacancy layers is formed at ∼200 °C, driven by the spontaneous precipitation of argyrodite-type Ag8GeTe6 which alters the stoichiometry of the TAGS-85 matrix. The rhombohedral and trigonal phases of TAGS-85 coexist up to 380 °C, above which a single cubic phase is obtained and the Ag8GeTe6 precipitates redissolve into the matrix. On subsequent cooling a mixture of rhombohedral, trigonal, and Ag8GeTe6 phases is again obtained. Initially single-phase samples exhibit thermoelectric power factors of up to 0.0035 W m–1 K–2 at 500 °C, a value that is maintained on subsequent thermal cycling and which represents the highest power factor yet reported for undoped TAGS-85. Therefore, control over the structural homogeneity of TAGS-85 as demonstrated here is essential in order to optimize the thermoelectric performance.

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Section: Resultssupporting

confidence: 89%

Phase Transitions of Thermoelectric TAGS-85

et al. 2017

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“…[13][14][15][16] Forming a solid solution has been successfully applied in many thermoelectric materials such as Si 1Àx Ge x , [17][18][19] Mg 2 Si 1Àx Sn x , [20][21][22] Bi 2Àx Sb x Te 3 (ref. [23][24][25][26] and half-Heusler 13,27,28 compounds.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric performance of SnS and SnS–SnSe solid solution

et al. 2015

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Solid solution is a potential way to optimize thermoelectric performance for its low thermal conductivity compared to those of the constituent compounds because of the phonon scattering from disordered atoms. Tin(II) sulfide (SnS) shows analogous band structure and electrical properties with tin selenide (SnSe), which was the motivation for investigating the thermoelectric performance of SnS and SnS-SnSe solid solution system. SnS compound and SnS 1Àx Se x (0 < x < 1) solid solution were fabricated using the melting method and they exhibited anisotropic thermoelectric performance along the parallel and perpendicular to the pressing directions. For the SnS compound, the maximum zT k value is 0.19 at 823 K along the parallel to pressing direction, which is higher than that along the perpendicular to the pressing direction (zT t ¼ 0.16). The zT values of SnS 0.5 Se 0.5 and SnS 0.2 Se 0.8 were higher than those of the SnS compound and a maximum zT value of 0.82 was obtained for SnS 0.2 Se 0.8 at 823 K, which is more than four times higher than that of SnS.

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“…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][7][8][9][10][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.…”

Section: Introductionmentioning

confidence: 99%

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

Xie

Yan

et al. 2017

NPG Asia Mater

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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

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Ioffe–Regel limit and lattice thermal conductivity reduction of high performance (AgSbTe₂)₁₅(GeTe)₈₅ thermoelectric materials

Cited by 66 publications

References 20 publications

Phase Transitions of Thermoelectric TAGS-85

Phase Transitions of Thermoelectric TAGS-85

Thermoelectric performance of SnS and SnS–SnSe solid solution

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

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