Ti Addition Effect on the Grain Structure Evolution and Thermoelectric Transport Properties of Hf0.5Zr0.5NiSn0.98Sb0.02 Half-Heusler Alloy

Cho, Junsang; Park, Taegyu; Bae, Ki Wook; Kim, Hyun-Sik; Choi, Soon‐Mok; Kim, Sang Il; Kim, Sung Wng

doi:10.3390/ma14144029

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…Zr, Hf, and Ta have been employed as heavy dopants for enhancing the thermoelectric properties of TiNiSn by lowering the phononic thermal conductivity. , The compositions investigated here are Ti 2– x Ta x NiCoSn 0.5 Sb 1.5 ( x = 0.1, 0.25, 0.5, and 1.0) and Ti 2– x Ta x NiCoSn 0.5 Sb 1.5 ( x = 0.05, 0.1, 0.15, 0.2, and 1.0), which were synthesized by the VAM-1 h BM-SPS route reported for Ti 2 NiCoSnSb . The density of the pellets is given in Table S1.…”

Section: Resultsmentioning

confidence: 99%

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Mishra

Tan

Trivedi

et al. 2023

ACS Appl. Energy Mater.

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The effect of doping on the thermoelectric properties of Half-Heusler (HH) high-entropy alloy (HEA) Ti2NiCoSnSb was studied. Lower thermal conductivity was observed with increased Sb doping. Mass scattering by heavy (Ta, Zr) and light (Al) dopants was studied to further lower the thermal conductivity. Dopants at the level of up to 50% at the Ti site were studied. A high HH phase content was obtained in the Zr-doped samples, and a low-lattice thermal conductivity of 1.9 W/(m·K) was observed. This value is one of the lowest reported lattice thermal conductivities in HH alloys. The poor solubility of Ta led to undissolved Ta in the samples, which enhanced the electrical properties. In the case of Al doping, the NiAl phase raised the power factor value of Ti1.8Al0.2NiCoSn0.5Sb1.5 to 2.2 × 10–3 W/(m·K2), which is almost twice the corresponding value reported for Ti2NiCoSnSb. Interestingly, a maximum ZT of 0.29 was found in all of the doped systems, although the transport mechanism and microstructure varied widely with the type of dopant. An optimum dopant level of 25% of Zr, 7.5% of Ta, and 10% of Al is necessary to obtain the maximum ZT in these alloys. Compared to HH systems, the HH high-entropy alloy (HEA) systems provide a larger composition field for tuning the transport properties by simultaneous doping of multiple elements to lower the thermal conductivity.

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Section: Resultsmentioning

confidence: 99%

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Mishra

Tan

Trivedi

et al. 2023

ACS Appl. Energy Mater.

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“…Real-world materials have grains of different sizes and orientations which scatter phonons differently. Domain sizes of 50 and 100 nm are assumed here, while depending on the preparation method, experimentally average grain sizes have been reported in the 60 to 400 nm range [62,93,94]. Nonetheless, gb-scattering provides some indication of how grains and other macroscopic defects filter out the contributions of mostly long-wavelength phonons to the LTC.…”

Section: Discussionmentioning

confidence: 99%

Attaining Low Lattice Thermal Conductivity in Half-Heusler Sublattice Solid Solutions: Which Substitution Site Is Most Effective?

Tranås

Løvvik

Berland

2022

Electronic Materials

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Low thermal conductivity is an important materials property for thermoelectricity. The lattice thermal conductivity (LTC) can be reduced by introducing sublattice disorder through partial isovalent substitution. Yet, large-scale screening of materials has seldom taken this opportunity into account. The present study aims to investigate the effect of partial sublattice substitution on the LTC. The study relies on the temperature-dependent effective potential method based on forces obtained from density functional theory. Solid solutions are simulated within a virtual crystal approximation, and the effect of grain-boundary scattering is also included. This is done to systematically probe the effect of sublattice substitution on the LTC of 122 half-Heusler compounds. It is found that substitution on the three different crystallographic sites leads to a reduction of the LTC that varies significantly both between the sites and between the different compounds. Nevertheless, some common criteria are identified as most efficient for reduction of the LTC: The mass contrast should be large within the parent compound, and substitution should be performed on the heaviest atoms. It is also found that the combined effect of sublattice substitution and grain-boundary scattering can lead to a drastic reduction of the LTC. The lowest LTC of the current set of half-Heusler compounds is around 2 W/Km at 300 K for two of the parent compounds. Four additional compounds can reach similarly low LTC with the combined effect of sublattice disorder and grain boundaries. Two of these four compounds have an intrinsic LTC above ∼15 W/Km, underlining that materials with high intrinsic LTC could still be viable for thermoelectric applications.

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Thermoelectric properties of Co doped TiNiCoxSn alloys fabricated by melt spinning

He,

Luo,

Wang

et al. 2024

Acta Phys. Sin.

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Although TiNiSn-based half-Heusler thermoelectric materials obtain high power factors, their high lattice thermal conductivity greatly hinders the improvement of thermoelectric properties. In this paper, TiNiCoxSn (x=0~0.05) samples were prepared by melt spinning combined with spark plasma sintering method and their phase, microstructure and thermoelectric properties are studied. The XRD results show that the main phase of all samples is TiNiSn phase, and no other impurity phases are found, indicating that the high purity single phase can be prepared by rapid quenching process combined with SPS process. During the solidification process, the large cooling rate (105-106 K/s) is conducive to obtaining the uniform nanocrystalline structure. The grains are closely packed with a grain size of 200-600 nm. The grain size decrease to 50-400 nm for the Co-doping samples, which indicates that Co doping can reduce the grain size. For the x=0 sample, the thermal conductivity of the rapid quenching sample is significantly lower than that of bulk sample, with an average decrease of about 17.8%. Compared with the TiNiSn matrix, the thermal conductivity of the Co-doping samples are significantly reduced, and the maximum decrease is about 38.9%. The minimum value of lattice thermal conductivity of TiNiCoxSn samples is 3.19 W/mK. Therefore, Co doping can significantly reduce the кl of TiNiCoxSn (x=0.01~0.05) samples. With the increase of Co doping amount x, n/p transition is observed in the TiNiCoxSn samples, resulting in a gradually decrease of the conductivity and the power factor, and finally the deterioration of the electrical transport performance. Among them, the TiNiSn sample obtains the highest power factor of 29.56 W/mK2 at 700 K. The zT value decreases with the Co doping amount x, and the maximum zT value of TiNiSn sample at 900 K is 0.48. This work shows that the thermal conductivity of TiNiSn can be effectively reduced by using the melt spinning process and magnetic Co doping.

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Ti Addition Effect on the Grain Structure Evolution and Thermoelectric Transport Properties of Hf0.5Zr0.5NiSn0.98Sb0.02 Half-Heusler Alloy

Cited by 3 publications

References 17 publications

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Attaining Low Lattice Thermal Conductivity in Half-Heusler Sublattice Solid Solutions: Which Substitution Site Is Most Effective?

Thermoelectric properties of Co doped TiNiCo<sub><i>x</i></sub>Sn alloys fabricated by melt spinning

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Ti Addition Effect on the Grain Structure Evolution and Thermoelectric Transport Properties of Hf0.5Zr0.5NiSn0.98Sb0.02 Half-Heusler Alloy

Cited by 3 publications

References 17 publications

Low-Lattice Thermal Conductivity in Zr-Doped Ti2NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Low-Lattice Thermal Conductivity in Zr-Doped Ti2NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Attaining Low Lattice Thermal Conductivity in Half-Heusler Sublattice Solid Solutions: Which Substitution Site Is Most Effective?

Thermoelectric properties of Co doped TiNiCo<sub><i>x</i></sub>Sn alloys fabricated by melt spinning

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Product

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Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys