Thermoelectric and thermophysical properties of TiCoSb, ZrCoSb, HfCoSb prepared by SPS

Sekimoto, Takeyuki; Kurosaki, Ken; Muta, Hiroaki; Yamasaka, Shuto

doi:10.1109/ict.2005.1519955

Cited by 20 publications

(43 citation statements)

References 18 publications

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“…[4][5][6][7] Since micro defects, phase separation and inhomogeneity created during materials processing could greatly influence the thermoelectric properties, careful control of microstructure with long time annealing are normally unavoidable. 1,3) Homogenous, single phase half-Heuslers are inherently difficult to produce in case of containing low meting point elements such as Sn or Sb, due to their easy of sublimation during high temperature processing. In order to address these problems, mechanical alloying (MA) process as a solid state synthesis was applied in this study.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5] Doping on this system was found to be effective in electrical property enhancement via band structure forming, and the substitution on the Zr and/or Ni site were shown to be decrease in thermal conductivity via point defect phonon scattering, resulting in enhanced thermoelectric properties. 3,6) The conduction type can also be modified by doping or substitution. 6) TiCoSb is generally prepared by induction melting, powder processing with hot pressing or spark plasma sintering, and/ or hybrid methods of these.…”

Section: Introductionmentioning

confidence: 99%

“…3) TiCoSb belongs to a half-Heusler structure and it is expected to be a promising thermoelectric material having relatively high figure of merit value, especially for power generation. 1,3) The figure of merit is defined as ZT = α 2 σT/ κ, where α is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity and T is the temperature in Kelvin. Undoped TiCoSb shows intrinsic ntype conduction.…”

Section: Introductionmentioning

confidence: 99%

“…The crystallographic sites (0,0,0) and (1/4, 1/4, 1/4) are occupied by two different transition metals, the (1/2, 1/2, 1/2) site is occupied by Sn, Sb, or Bi, and the site (3/4, 3/4, 3/4) is empty. [3][4] Candidates with this structure for the investigation would be categorized into the combination of (Ti/Zr/Hf)(Co/Ni/Pt)(Sb/Sn/ Bi). 3) TiCoSb belongs to a half-Heusler structure and it is expected to be a promising thermoelectric material having relatively high figure of merit value, especially for power generation.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4] Candidates with this structure for the investigation would be categorized into the combination of (Ti/Zr/Hf)(Co/Ni/Pt)(Sb/Sn/ Bi). 3) TiCoSb belongs to a half-Heusler structure and it is expected to be a promising thermoelectric material having relatively high figure of merit value, especially for power generation. 1,3) The figure of merit is defined as ZT = α 2 σT/ κ, where α is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity and T is the temperature in Kelvin.…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties of Half-Heusler TiCoSb Synthesized by Mechanical Alloying Process

Ur¹

2011

Korean. J. Mater. Res.

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Half-Heusler alloys are a potential thermoelectric material for use in high-temperature applications. In an attempt to produce half-Heusler thermoelectric materials with fine microstructures, TiCoSb was synthesized by the mechanical alloying of stoichiometric elemental powder compositions and then consolidated by vacuum hot pressing. The phase transformations during the mechanical alloying and hot consolidation process were investigated using XRD and SEM. A single-phase, halfHeusler allow was successfully produced by the mechanical alloying process, but a minor portion of the second phase of the CoSb formation was observed after the vacuum hot pressing. The thermoelectric properties as a function of the temperature were evaluated for the hot-pressed specimens. The Seebeck coefficients in the test range showed negative values, representing n-type conductivity, and the absolute value was found to be relatively low due to the existence of the second phase. It is shown that the electrical conductivity is relatively high and that the thermal conductivities are compatibly low in MA TiCoSb. The maximum ZT value was found to be relatively low in the test temperature range, possibly due to the lower Seebeck coefficient. The Hall mobility value appeared to be quite low, leading to the lower value of Seebeck coefficient. Thus, it is likely that the single phase produced by mechanical alloying process will show much higher ZT values after an excess Ti addition. It is also believed that further property enhancement can be obtained if appropriate dopants are selectively introduced into this MA TiCoSb System.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermoelectric Properties of Half-Heusler TiCoSb Synthesized by Mechanical Alloying Process

Ur¹

2011

Korean. J. Mater. Res.

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Thermoelectric Properties of the XCoSb (X: Ti,Zr,Hf) Half‐Heusler alloys

Gandi

Schwingenschlögl

2017

Physica Status Solidi (b)

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We investigate the thermoelectric properties of the half‐Heusler alloys XCoSb (X: Ti,Zr,Hf) by solving Boltzmann transport equations and discuss them in terms of the electronic band structure. The rigid band approximation is employed to address the effects of doping. While many half‐Heuser alloys show excellent thermoelectric performance, the materials under study are special by supporting both n‐ and p‐doping. We identify the reasons for this balanced thermoelectric transport and explain why experimentally p‐doping is superior to n‐doping. We also determine the spectrum of phonon mean free paths to guide grain refinement methods to enhance the thermoelectric figure of merit.

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High‐Pressure‐Sintering‐Induced Microstructural Engineering for an Ultimate Phonon Scattering of Thermoelectric Half‐Heusler Compounds

Zhu

Ying

et al. 2021

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Thermal management is of vital importance in various modern technologies such as portable electronics, photovoltaics, and thermoelectric devices. Impeding phonon transport remains one of the most challenging tasks for improving the thermoelectric performance of certain materials such as half‐Heusler compounds. Herein, a significant reduction of lattice thermal conductivity (κL) is achieved by applying a pressure of ≈1 GPa to sinter a broad range of half‐Heusler compounds. Contrasting with the common sintering pressure of less than 100 MPa, the gigapascal‐level pressure enables densification at a lower temperature, thus greatly modifying the structural characteristics for an intensified phonon scattering. A maximum κL reduction of ≈83% is realized for HfCoSb from 14 to 2.5 W m−1 K−1 at 300 K with more than 95% relative density. The realized low κL originates from a remarkable grain‐size refinement to below 100 nm together with the abundant in‐grain defects, as determined by microscopy investigations. This work uncovers the phonon transport properties of half‐Heusler compounds under unconventional microstructures, thus showing the potential of high‐pressure compaction in advancing the performance of thermoelectric materials.

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Thermoelectric and thermophysical properties of TiCoSb, ZrCoSb, HfCoSb prepared by SPS

Cited by 20 publications

References 18 publications

Thermoelectric Properties of Half-Heusler TiCoSb Synthesized by Mechanical Alloying Process

Thermoelectric Properties of Half-Heusler TiCoSb Synthesized by Mechanical Alloying Process

Thermoelectric Properties of the XCoSb (X: Ti,Zr,Hf) Half‐Heusler alloys

High‐Pressure‐Sintering‐Induced Microstructural Engineering for an Ultimate Phonon Scattering of Thermoelectric Half‐Heusler Compounds

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