Record Seebeck coefficient and extremely low thermal conductivity in nanostructured SnSe

Serrano‐Sánchez, Federico; Gharsallah, M.; Nemes, N. M.; Mompeán, F. J.; Martínez, José Luis; Alonso, J. A.

doi:10.1063/1.4913260

Cited by 75 publications

(81 citation statements)

References 18 publications

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“…The comparison of the (Sn,Ge)-Se bond lengths, of 2.745(2) and 2.7897(13) (x2) Å for the x = 0.2 compound, with those observed for pristine SnSe22, (2.750(4) and 2.798(2) (x2) Å) shows that the coordination polyhedra become smaller upon Ge introduction, as expected. It is also interesting to consider the interlayer distances, given by Sn-Se bond lengths parallel to the a axis, shortening from pure SnSe (3.465(4) Å)22 to Sn 0.8 Ge 0.2 Se (3.457(4) Å, Table 2), concomitant with the reduction of the a unit-cell parameter. Additionally, the analysis of the neutron data yielded accurate anisotropic displacement factors for all the atoms, displayed in Fig.…”

Section: Resultssupporting

confidence: 70%

Giant Seebeck effect in Ge-doped SnSe

Gharsallah

Serrano‐Sánchez

Nemes

et al. 2016

Sci Rep

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Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples. Ge does not dope the system in the sense of donating carriers, yet the electrical properties show a semiconductor behavior with resistivity values higher than that of the parent compound, as a consequence of nanostructuration, whereas the Seebeck coefficient is higher and thermal conductivity lower, favorable to a better ZT figure of merit.

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Section: Resultssupporting

confidence: 70%

Giant Seebeck effect in Ge-doped SnSe

Gharsallah

Serrano‐Sánchez

Nemes

et al. 2016

Sci Rep

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“…The inset is the schematic diagram for the cutting direction. [8,12,13,17,18] It is well known that the high-T Cmcm SnSe has a narrower band gap (≈0.39 eV) than its corresponding low-T Pnma structure (≈0.61 eV). The first region is from 323 to 600 K, in which the σ values of the pristine and Ag-doped samples decrease quickly as the temperature increases, indicating their metal-like behavior.…”

Section: Thermoelectric Properties Of Pristine Ag-and Sncl 2 -Doped mentioning

confidence: 99%

Three‐Stage Inter‐Orthorhombic Evolution and High Thermoelectric Performance in Ag‐Doped Nanolaminar SnSe Polycrystals

Zhang

Wang

Sun

et al. 2017

Advanced Energy Materials

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generation in deep-space and waste heat recovery from vehicle exhaust, as well as ice-free refrigeration in wine-storage cabinets, hotel room mini-refrigerators, and office water coolers. [1][2][3][4][5] The performance of TE materials is determined by the dimensionless figure of merit (ZT), defined as ZT = α 2 σT/(κ lat + κ ele ), where α, σ, κ lat , κ ele , and T are the Seebeck coefficient, electrical conductivity, lattice thermal conductivity, electronic thermal conductivity, and absolute temperature, respectively. The conversion efficiency for these potential applications requires high ZT over a wide range of temperatures. [6] For effective waste heat recovery in vehicles under a 350 K temperature differential, the average or device ZT (ZT dev ) should be about 1.25 in order to increase mileage up to 10%, [1,7] while for primary power generation, an average ZT of more than 1.5 is required under an 800 K temperature differential. [1,7] Recently, SnSe single crystals have produced a surge in the field of thermoelectrics as a new type of promising TE materials because of the intrinsically ultralow thermal conductivity (<0.4 W m −1 K −1 at 923 K) and high ZT along the b-and c-crystallographic directions (>2.3 at 923 K). [8] A new record of ZT dev ≈ 1.34 from 300-773 K along the b-crystallographic direction was achieved in thermoelectric device fabricated from hole-doped SnSe single crystal. [9] Nevertheless, the difficulties in large-scale synthesis of single crystals limit their practical applications, and extensive efforts have been devoted to the fabrication of high-performance polycrystalline counterparts. [10][11][12][13][14][15] For example, Wei et al. [12] reported a ZT of ≈0.8 at 800 K in 1% Na-and K-doped SnSe, which was produced by conventional solid state reaction followed by a spark plasma sintering (SPS) treatment. Due to an impressively low lattice thermal conductivity (≈0.20 W m −1 K −1 at 773 K) arising from the presence of coherent nanoprecipitates in the SnSe matrix, a high ZT of ≈1.1 at 773 K was achieved in the direction perpendicular to the pressing direction of SPS for ball-milled K-doped SnSe. [11] Apart from p-type alkali dopants (Li, Na, K), n-type dopants such as I and BiCl 3 are also adopted to improve the performance of polycrystalline SnSe. [14,16] For instance, a ZT of ≈0.8 at 773 K was obtained in I-doped SnSe polycrystals, whichThe ultrahigh thermoelectric performance of SnSe-based single crystals has attracted considerable interest in their polycrystalline counterparts. However, the temperature-dependent structural transition in SnSe-based thermoelectric materials and its relationship with their thermoelectric performance are not fully investigated and understood. In this work, nanolaminar SnSe polycrystals are prepared and characterized in situ using neutron and synchrotron powder diffraction measurements at various temperatures. Rietveld refinement results indicate that there is a complete inter-orthorhombic evolution from Pnma to Cmcm by a series of layer slips and stretches a...

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“…The highest reported ZT for polycrystalline SnSe is only 1.1, which is less than half of the undoped SC. 15,16 Even though alloying and microstructure modulation have been used to reduce thermal conductivity, polycrystalline samples exhibit a higher κ than the SC, [15][16][17][18][19][20] which contradicts phonon scattering considering the effect of grain boundary scattering. In addition, most polycrystalline samples possess lower power factors (S 2 σ) than the SC, which suggests that the control of crystallite orientation is very important in polycrystalline SnSe samples.…”

Section: Introductionmentioning

confidence: 98%

“…In addition, most polycrystalline samples possess lower power factors (S 2 σ) than the SC, which suggests that the control of crystallite orientation is very important in polycrystalline SnSe samples. [15][16][17][18][19][20] The undoped SnSe shows a carrier concentration of~10 17 cm − 3 , 11 which is considerably lower than the optimal region for a thermoelectric material. [2][3][4] Therefore, chemical doping has been used to tune the carrier concentration and improve the thermoelectric performance of SnSe.…”

Section: Introductionmentioning

confidence: 99%

Texturing degree boosts thermoelectric performance of silver-doped polycrystalline SnSe

Wang

Liu

et al. 2017

NPG Asia Mater

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Tin selenite (SnSe) has attracted significant attention due to its record thermoelectric figure of merit (ZT = 2.6 at 923 K) of its single crystal. However, the polycrystalline SnSe processes considerably less ZTs (⩽1.1). In this study, we investigate the thermoelectric properties of Ag-doped polycrystalline SnSe, which was synthesized via zone melting and hot pressing. By comparing our results and previous reports of Ag-doped single crystals and polycrystals, we determine that the high texturing degree is essential for achieving good thermoelectric performance in polycrystalline SnSe. The zone-melted Sn 0.99 Ag 0.02 Se shows better thermoelectric performance than the Ag-doped SnSe single crystal in the entire temperature range, exhibiting a peak ZT of 1.3 at 793 K.

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Record Seebeck coefficient and extremely low thermal conductivity in nanostructured SnSe

Cited by 75 publications

References 18 publications

Giant Seebeck effect in Ge-doped SnSe

Giant Seebeck effect in Ge-doped SnSe

Three‐Stage Inter‐Orthorhombic Evolution and High Thermoelectric Performance in Ag‐Doped Nanolaminar SnSe Polycrystals

Texturing degree boosts thermoelectric performance of silver-doped polycrystalline SnSe

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