Effect of C and N Addition on Thermoelectric Properties of TiNiSn Half-Heusler Compounds

Dow, Hwan Soo; Kim, Woo Sik; Shin, Weon Ho

doi:10.3390/ma11020262

Cited by 5 publications

(4 citation statements)

References 40 publications

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“…Over the last few decades, half-Heusler (HH) compounds, a type of thermoelectric material, have been given a lot of attention for their desirable characteristics, such as excellent mechanical robustness, good TE performance, high-temperature stability, and low toxicity, all of which are of great significance for TE materials’ practical applications [10,11,12]. The properties of HH compounds are strongly influenced by the number of valence electrons in a unit cell; HH compounds with a number of 18 valence electrons are typically semiconductors, and M I NiSn, M I CoSb (M I = Ti, Zr, Hf), M II FeSb (M II = Nb, V), and their alloys have been extensively investigated as promising TE materials applicated at medium-high temperature [13,14,15,16,17,18,19,20,21,22].…”

Section: Introductionmentioning

confidence: 99%

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy

Huang

Wang

et al. 2019

Materials

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The effects of V vacancy on the thermoelectric performance of the half-Heusler compound VCoSb have been investigated in this study. A certain amount of CoSb secondary phase is generated in the VCoSb matrix when the content of V vacancy is more than 0.1 at%. According to the results, a ZT value of 0.6, together with a power factor of 29 μW cm−1 K−2 at 873 K, were achieved for the nonstoichiometric sample V0.9CoSb. This proved that moderate V vacancy could improve the thermoelectric (TE) properties of VCoSb. The noticeable improvements are mainly owing to the incremental Seebeck coefficient, which may benefit from the optimized carrier concentration. However, too much V vacancy will result in more CoSb impurity and deteriorate the TE performances of VCoSb owing to the increased thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy

Huang

Wang

et al. 2019

Materials

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“…Recently, particular attention has been paid to half-Heusler (HH) compounds, due to their high-temperature stability, good mechanical robustness, and good TE performance, which are of paramount importance for practical applications. Typical semiconducting HH compounds with 18 valence electrons per unit cell, ZrCoSb, ZrNiSn, TiNiSn, NbFeSb, and their alloys have been intensively investigated as promising medium–high temperature TE materials [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Additionally, an exciting ZT of about 1.5 at 1200 K has been realized in p-type NbFeSb alloys [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Excess Co on the Phase Composition and Thermoelectric Properties of Half-Heusler NbCoSb

et al. 2018

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NbCoSb with nominal 19 valence electrons, and is supposed to be metallic, has recently been reported to also exhibit the thermoelectric properties of a heavily doped n-type semiconductor. In this study, we prepared Co-rich NbCo1+xSb samples (x = 0, 0.2, 0.3, 0.4, 0.5), and their phase compositions, microstructures and thermoelectric properties were investigated. The Seebeck coefficient increased a great deal with increasing x, due to decreasing carrier concentration, and the total thermal conductivity reduced mainly because of declining κe. Finally, a peak thermoelectric figure of merit, ZT, was about 0.46 for NbCo1.3Sb at 973 K. This enhancement was mainly attributed to the reduction of electric thermal conductivity and the increase of Seebeck coefficient. The excess Co had effects on the carrier concentration, deformation potential Edef and DOS effective mass m*. Adding an excessive amount of Co leads to a very high Edef, which was detrimental for transport characteristics.

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“…The aim of this work was to develop a good p-type thermoelectric material based on TiCoSb that avoids the use of expensive Zr and Hf. Compared to TiNiSn (see e.g., [16][17][18][19][20][21][22][23][24][25]), TiCoSb has attracted far less interest and does not support the presence of interstitial Co for samples prepared using powder routes [26]. Previous work from our group showed that co-substitution with V and Sn improved the high-temperature stability of TiCoSb [26].…”

Section: Introductionmentioning

confidence: 99%

Substitution Versus Full-Heusler Segregation in TiCoSb

Asaad

Buckman

Bos

2018

Metals

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Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb.

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Effect of C and N Addition on Thermoelectric Properties of TiNiSn Half-Heusler Compounds

Cited by 5 publications

References 40 publications

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy

The Effects of Excess Co on the Phase Composition and Thermoelectric Properties of Half-Heusler NbCoSb

Substitution Versus Full-Heusler Segregation in TiCoSb

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