Thermoelectric Properties of (Ti,Zr,Hf)CoSb Type Half-Heusler Compounds

Sekimoto, Takeyuki; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinşuke

doi:10.2320/matertrans.46.1481

Cited by 55 publications

(40 citation statements)

References 34 publications

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“…It is considered that these Hf-rich impurity phases may induce the reduction of . On the other hand, we have confirmed that the as-cast HfCoSb sample 11) contains the Hf-rich impurity phases in the XRD pattern. It is not always true that just only a segregation of Hf-rich impurity phases is responsible for small .…”

Section: Resultssupporting

confidence: 63%

“…6) It is considered that the differences of the between the present and previous studies 11) are mainly due to the deviation from the stoichiometric composition as well as the relaxation of the structural disorder effect by annealing.…”

Section: Resultsmentioning

confidence: 96%

“…The of TiCoSb, ZrCoSb and HfCoSb are larger than those of as-cast samples reported in the previous study. 11) It is well known that the annealing condition 10,[13][14][15] and the deviation from the stoichiometric composition 6) have much effect on the thermoelectric properties of the half-Heusler compounds. For example, the of TiCoSb tends to increase with decreasing the Co/Sb ratio and with increasing the Ti/Sb ratio.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4][5] The theoretically calculated band gap energy of TiCoSb (0.95, 1) 0.82 eV 5) ) is larger than that of the similar material TiNiSn (0.42 eV, 1) 0.51 2) ). So, TiCoSb is expected to have a larger thermoelectric power S. From the literatures, [6][7][8][9][10][11] TiCoSb has a negative thermoelectric power. The improvement of the structural disorder 12) by annealing has been reported on MNiSn system [13][14][15] and TiCoSb system.…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric and Thermophysical Properties of TiCoSb-ZrCoSb-HfCoSb Pseudo Ternary System Prepared by Spark Plasma Sintering

et al. 2006

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We studied the thermoelectric and thermophysical properties of TiCoSb-ZrCoSb-HfCoSb pseudo ternary system. Polycrystalline samples were prepared by a spark plasma sintering (SPS) technique, and their thermoelectric properties above room temperature and thermophysical properties at room temperature were measured. All the samples were identified as a half-Heusler compound by the X-ray diffraction analysis. The lattice parameter, electrical resistivity and thermoelectric power systematically change with the composition in the pseudo ternary phase diagram. All the samples indicated negative values of the thermoelectric power. Low thermal conductivity was achieved in the samples with the composition near the center of the pseudo ternary phase diagram where the effect of the alloy scattering becomes large. The maximum value of ZT was obtained to be 0.073 at 790 K for Ti 0:25 (Zr 0:5 Hf 0:5 ) 0:75 CoSb.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermoelectric and Thermophysical Properties of TiCoSb-ZrCoSb-HfCoSb Pseudo Ternary System Prepared by Spark Plasma Sintering

et al. 2006

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“…The relaxed lattice constants of undoped and doped TiCoSb are summarized in Table 1. For Ti/Zr/HfCoSb, the optimized lattice constants are in good agreement with the experimental [25] and other theoretical results [24] [26], with slight overestimates typical of the GGA [27]. The above results indicate that the crystal model was rational and could be used for computational prediction.…”

Section: Crystal Structuressupporting

confidence: 75%

First-Principles Investigation of the Effect of M-Doped (M = Zr, Hf) TiCoSb Half-Heusler Thermoelectric Material

Sun¹,

Li²,

Zhao³

et al. 2015

MSCE

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The M-doping (M = Zr, Hf) effects on the electronic structures and thermoelectric performance of TiCoSb were studied by first-principles calculations. The band structure analysis shows that substituting Ti with M does not change the band structures of these systems significantly. Most of the M-doped systems have a lower band gap value than that of TiCoSb; especially Ti 0.5 Zr 0.5 CoSb has the lowest energy band gap value of 0.971 eV. Besides, the amplitudes of the density of states in the region of the valence bands for M-doped systems show a similar but slightly higher value than TiCoSb. Those suggest that these compounds could have better thermoelectric performance than TiCoSb. The phonon dispersion relations show that the larger mass of Zr/Hf with respect to Ti lowers the optical modes and induces mixing with the acoustic branches. Our calculations offer a valuable insight on how to characterize complicated crystal structures of thermoelectric materials and optimize the material composition.

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A comparative investigation of different exchange‐correlation functionals oriented prediction of structural, electronic, optical, and transport properties of the novel quaternary LiTiCoSn

Abraham

Sharma

Dar³

et al. 2022

Intl J of Energy Research

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Summary The ground state structural, mechanical, electronic, vibrational, optical, and thermoelectric properties of the newly synthesized quaternary LiTiCoSn compound is deliberated elaborately with the help of ab‐initio tactics formulated under the framework of density functional theory. The calculated results of equilibrium structural parameters are observed to be in fairly good agreement with the available similar theoretical as well as experimental data. Structural optimization has been done for three diverse crystal structure configurations that is, Type 1, Type 2, and Type 3. After studying optimization curves, it is found that Type 2 crystal structure is the most stable structure for this compound as it possesses the minimum energy. The structural stability of this compound has been explored using three different exchange correlation functions that is, PBE‐GGA, WC‐GGA, and PBE‐sol GGA for better understanding. It is found from our studies that the inclusion of the electronic exchange‐correlation through the newly developed Trans‐Blaha modified Beck‐Johnson potential (TB‐mBJ) along with PBE‐GGA expands the portrayal of the obtained electronic band plots. Insertion of TB‐mBJ potential vintages an indirect energy gap (Γ–X) of 1.052 eV for the studied compound, which reveals its semiconducting nature. Also, the elastic constants (Cij) and the associated elastic moduli confirm its stability in the cubic phase and demonstrate its brittle nature. Furthermore, spectral dependency of dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity, energy loss function, and optical conductivity on incident electromagnetic radiations up to 8 eV are also studied. The maximum power factor for the studied LiTiCoSn compound is obtained as 7.35 mWm−1 K−2 at room temperature, which increases to 17.10 mWm−1 K−2 at 700 K and 22.50 mWm−1 K−2 at 1200 K, respectively. So LiTiCoSn can be a novel sort of intriguing thermoelectric material as well as it can be used in optoelectronic and energy harvesting devices.

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Thermoelectric Properties of (Ti,Zr,Hf)CoSb Type Half-Heusler Compounds

Cited by 55 publications

References 34 publications

Thermoelectric and Thermophysical Properties of TiCoSb-ZrCoSb-HfCoSb Pseudo Ternary System Prepared by Spark Plasma Sintering

Thermoelectric and Thermophysical Properties of TiCoSb-ZrCoSb-HfCoSb Pseudo Ternary System Prepared by Spark Plasma Sintering

First-Principles Investigation of the Effect of M-Doped (M = Zr, Hf) TiCoSb Half-Heusler Thermoelectric Material

A comparative investigation of different exchange‐correlation functionals oriented prediction of structural, electronic, optical, and transport properties of the novel quaternary LiTiCoSn

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