Effect of the Zr0.5Hf0.5CoSb1-xSnx/HfO2 half-Heusler nanocomposites on the ZT value

Hsu, Chun-Chen; Liu, Yion-Ni; Ma, Hwong‐Wen

doi:10.1016/j.jallcom.2014.01.208

Cited by 24 publications

(16 citation statements)

References 20 publications

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“…4,5,7,11,12 However, the relatively high thermal conductivity is an obstacle to implementing Heusler TE's. M is either Ti, Zr, or Hf or a combination of these elements.…”

Section: Introductionmentioning

confidence: 99%

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Rausch

Balke

Ouardi

et al. 2014

Phys. Chem. Chem. Phys.

122

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A novel approach for optimization of the thermoelectric properties of p-type Heusler compounds with a C1b structure was investigated. A successful recipe for achieving intrinsic phase separation in the n-type material based on the TiNiSn system is isoelectronic partial substitution of Ti with its heavier homologues Zr and Hf. We applied this concept to the p-type system MCoSb0.8Sn0.2 by a systematic investigation of samples with different compositions at the Ti position (M = Ti, Zr, Hf, Ti0.5Zr0.5, Zr0.5Hf0.5, and Ti0.5Hf0.5). We thus achieved an approximately 40% reduction of the thermal conductivity and a maximum figure of merit ZT of 0.9 at 700 °C. This is a 80% improvement in peak ZT from 0.5 to 0.9 at 700 °C compared to the best published value of an ingot p-type half-Heusler compound. Thus far, comparable good thermoelectric p-type materials of this structure type have only been realized by a nanostructuring process via ball milling of premelted ingot samples followed by a rapid consolidation method, like hot pressing. The herein-presented simple arc-melting fabrication method reduces the fabrication time as compared to this multi-step nanostructuring process. The high mechanical stability of the Heusler compounds is favorable for the construction of thermoelectric modules. The Vickers hardness values are close to those of the n-type material, leading to good co-processability of both materials.

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“…4,5,7,11,12 However, the relatively high thermal conductivity is an obstacle to implementing Heusler TE's. M is either Ti, Zr, or Hf or a combination of these elements.…”

Section: Introductionmentioning

confidence: 99%

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Rausch

Balke

Ouardi

et al. 2014

Phys. Chem. Chem. Phys.

122

View full text Add to dashboard Cite

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“…The main strategy for increasing the ZT value of HH alloys consists of reducing thermal conductivity through enhanced phonon scattering. Alternatively, thermal conductivity of HH alloys is reduced using second phases as additional phonon scattering centers in the samples [28][29] . Alternatively, thermal conductivity of HH alloys is reduced using second phases as additional phonon scattering centers in the samples [28][29] .…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of Ge doped n-type Ti_xZr_1−xNiSn_0.975Ge_0.025half-Heusler alloys

Liu

Poudeu

2015

J. Mater. Chem. A

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Several compositions of the n-type, Ti x Zr 1-x NiSn 0.975 Ge 0.025 (x = 0, 0.1, 0.15 and 0.25), half-Heusler (HH) alloys were synthesized by reacting elemental powders at high temperature using induction melting. The resulting ingots were annealed at 900 °C for 2 weeks and mechanically alloyed to achieve fine grain size. X-ray powder diffraction suggested the formation of products with HH structure. However, electron microscopy studies revealed phase separation into Ti-rich and Zr-rich domains for the ingot with x = 0.25. The effect of band gap engineering through isoelectronic substitution of Sn by Ge and mass fluctuation arising from the intermixing of Ti and Zr in the HH structure on the electronic and thermal transports in the temperature range from 300 K to 775 K was investigated. A large reduction in the lattice thermal conductivity (4.9 W/Km to 2.8 W/Km at 300 K) was observed with increasing Ti concentration. Surprisingly, the thermopower and electrical conductivity for the sample with x = 0.25 simultaneously increase with rising temperature from -120 µV/K and 510 S/cm at 300 K to -160 µV/K and 840 S/cm at 775 K. The combination of large reduction in lattice thermal conductivity via mass fluctuation at the Ti/Zr site with optimization of the thermopower and electrical conductivity through Ge substitution at the Sn site significantly improved the figure of merit from 0.05 to 0.48 at 775 K for the sample with x = 0.25.

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“…Furthermore, a TEG modulus was also applied to study parameters such as output voltage and power generation. Hsu et al [22] studied the effect of grin refinement to the ZT value of new thermoelectric material, with high temperature working conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Zr0.5Hf0.5CoSb1-xSnx/HfO2 half-Heusler nanocomposites on the ZT value

Cited by 24 publications

References 20 publications

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Thermoelectric properties of Ge doped n-type Ti_xZr_1−xNiSn_0.975Ge_0.025half-Heusler alloys

Waste heat recovery using a thermoelectric power generation system in a biomass gasifier

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Effect of the Zr0.5Hf0.5CoSb1-xSnx/HfO2 half-Heusler nanocomposites on the ZT value

Cited by 24 publications

References 20 publications

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb0.8Sn0.2 system via phase separation

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb0.8Sn0.2 system via phase separation

Thermoelectric properties of Ge doped n-type TixZr1−xNiSn0.975Ge0.025half-Heusler alloys

Waste heat recovery using a thermoelectric power generation system in a biomass gasifier

Contact Info

Product

Resources

About

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb_0.8Sn_0.2 system via phase separation

Thermoelectric properties of Ge doped n-type Ti_xZr_1−xNiSn_0.975Ge_0.025half-Heusler alloys