Computational prediction of high thermoelectric performance in p-type half-Heusler compounds with low band effective mass

Fang, Teng; Zheng, Shuqi; Zhou, Tian; Yan, Lei; Zhang, Peng

doi:10.1039/c6cp07897d

Cited by 92 publications

(68 citation statements)

References 53 publications

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“…Calculations by other groups have also revealed that the 4d electrons of Nb and 5d electrons of Ta are similar when forming chemical bonds. [47] In addition, the band gap of TaFeSb is larger than that of NbFeSb, which may be favorable for better TE performance at higher temperature due to the suppression of the bipolar effect. [38] Therefore, Ta alloying in p-type NbFeSb based HH materials is highly desirable for further boosting the zT of this system.…”

Section: Introductionmentioning

confidence: 99%

Unique Role of Refractory Ta Alloying in Enhancing the Figure of Merit of NbFeSb Thermoelectric Materials

Liu

et al. 2017

Advanced Energy Materials

201

157

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NbFeSb‐based half‐Heusler alloys have been recently identified as promising high‐temperature thermoelectric materials with a figure of merit zT > 1, but their thermal conductivity is still relatively high. Alloying Ta at the Nb site would be highly desirable because the large mass fluctuation between them could effectively scatter phonons and reduce the lattice thermal conductivity. However, practically it is a great challenge due to the high melting point of refractory Ta. Here, the successful synthesis of Ta‐alloyed (Nb1−xTax)0.8Ti0.2FeSb (x = 0 – 0.4) solid solutions with significantly reduced thermal conductivity by levitation melting is reported. Because of the similar atomic sizes and chemistry of Nb and Ta, the solid solutions exhibit almost unaltered electrical properties. As a result, an overall zT enhancement from 300 to 1200 K is realized in the single‐phase Ta‐alloyed solid solutions, and the compounds with x = 0.36 and 0.4 reach a maximum zT of 1.6 at 1200 K. This work also highlights that the isoelectronic substitution by atoms with similar size and chemical nature but large mass difference should reduce the lattice thermal conductivity but maintain good electrical properties in thermoelectric materials, which can be a guide for optimizing the figure of merit by alloying.

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Section: Introductionmentioning

confidence: 99%

Unique Role of Refractory Ta Alloying in Enhancing the Figure of Merit of NbFeSb Thermoelectric Materials

Liu

et al. 2017

Advanced Energy Materials

201

157

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“…The thermoelectric figure of merit is given by the equation ZT=S 2 σT/κ and several theoretical and experimental studies which aim to optimise the thermal conductivity (κ) as well as the Seebeck coefficient (S) and electrical conductivity (σ) have been conducted in the past couple of years [1,2,[4][5][6][7][8][9][10]. This optimisation is done by p-type doping with Ti, Hf and Zr for Nb or Sn for Sb.…”

Section: Introductionmentioning

confidence: 99%

Huge power factor in p-type half-Heusler alloys NbFeSb and TaFeSb

et al. 2019

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NbFeSb is a promising thermoelectric material which according to experimental and theoretical studies exhibits a high power factor of up to 10 mW m −1 K −2 at room temperature and ZT of 1 at 1000 K. In all previous theoretical studies, κ latt is calculated using simplified models, which ignore structural defects. In this work, we calculate κ latt by solving the Boltzmann transport equation and subsequently including the contributions of grain boundaries, point defects and electron-phonon interaction. The results for κ latt and ZT are in excellent agreement with experimental measurements. In addition, we investigate theoretically the thermoelectric properties of TaFeSb. The material has recently been synthesised experimentally, thus confirming the theoretical hypothesis for its stability. This encourages a full-scale computation of its thermoelectric performance. Our results show that TaFeSb is indeed an excellent thermoelectric material which has a very high power factor of 16 mW m −1 K −2 at room temperature and ZT of 1.5 at 1000 K.

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“…For instance, CoTiSb has N v = 18, M = 0, and is a nonmagnetic semiconductor 24,[26][27][28] . In the past two decades, a large number of hH alloys have been reported to exhibit substantial TE properties comparable to conventional Bi 2 Te 3 and PbTe based materials [29][30][31][32][33][34][35][36] More recently, Zunger and coworkers, with the aid of first-principles calculations, systematically investigated the cobalt, rhodium, and iridium based 18-VEC hH alloys and revealed some new thermodynamically stable systems 37 . In addition, for the first time, they experimentally realized the CoTaSn system.…”

Section: Introductionmentioning

confidence: 99%

Ab initio design of new cobalt-based half-Heusler materials for thermoelectric applications

Zeeshan

Singh

Brink

et al. 2017

Phys. Rev. Materials

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In search of new prospects for thermoelectric materials, using ab-initio calculations and semiclassical Boltzmann theory, we have systematically investigated the electronic structure and transport properties of 18-valence electron count cobalt based half-Heusler alloys with prime focus on CoVSn, CoNbSn, CoTaSn, CoMoIn, and CoWIn. The effect of doping on transport properties has been studied under the rigid band approximation. The maximum power factor, S 2 σ, for all systems is obtained on hole doping and is comparable to the existing thermoelectric material CoTiSb. The stability of all the systems is verified by phonon calculations. Based on our calculations, we suggest that CoVSn, CoNbSn, CoTaSn, CoMoIn and CoWIn could be potential candidates for high temperature thermoelectric materials.

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Computational prediction of high thermoelectric performance in p-type half-Heusler compounds with low band effective mass

Cited by 92 publications

References 53 publications

Unique Role of Refractory Ta Alloying in Enhancing the Figure of Merit of NbFeSb Thermoelectric Materials

Unique Role of Refractory Ta Alloying in Enhancing the Figure of Merit of NbFeSb Thermoelectric Materials

Huge power factor in p-type half-Heusler alloys NbFeSb and TaFeSb

Ab initio design of new cobalt-based half-Heusler materials for thermoelectric applications

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