Synthesis and Thermoelectric Properties of ZrxTi1−xNiSn0.98Sb0.02n-Type Half-Heusler Materials

Hf-free Zr x Ti 1− x NiSn 0.98 Sb 0.02 ( x  = 0.25, 0.5, 0.75) n -type half-Heusler (HH) thermoelectric materials were synthesized by a serial processing method including induction melting (IM), annealing, ball milling, and spark plasma sintering (SPS). For comparison, a Hf-containing half-Heusler H...

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Bibliographic Details
Published in:Journal of electronic materials 2021, Vol.50 (7), p.4178-4185
Main Authors: Joo, Sung-Jae, Son, Ji-Hee, Lee, Ho Seong, Jang, Jeongin, Kim, Bong-Seo, Min, Bok-Ki
Format: Article
Language:English
Subjects:
Alloying
Ball milling
Characterization and Evaluation of Materials
Chemistry and Materials Science
Electric arc melting
Electronics and Microelectronics
Figure of merit
Heat conductivity
Heat transfer
Inclusions
Induction melting
Instrumentation
Materials Science
Optical and Electronic Materials
Original Research Article
Plasma sintering
Power factor
Solid State Physics
Spark plasma sintering
Stoichiometry
Thermal conductivity
Thermoelectric materials
Zirconium
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Summary:Hf-free Zr x Ti 1− x NiSn 0.98 Sb 0.02 ( x  = 0.25, 0.5, 0.75) n -type half-Heusler (HH) thermoelectric materials were synthesized by a serial processing method including induction melting (IM), annealing, ball milling, and spark plasma sintering (SPS). For comparison, a Hf-containing half-Heusler Hf 0.25 Zr 0.25 Ti 0.5 NiSn 0.98 Sb 0.02 ingot was also alloyed by arc melting, and the effects of Hf on the thermoelectric properties were estimated. The Zr x Ti 1− x NiSn 0.98 Sb 0.02 HH materials were nearly pure according to the x-ray diffraction analysis, but microscopic investigation revealed impurity phase inclusions of unalloyed Sn, Zr, and Ti. The power factor (PF) of the Hf-free HH materials reached the maximum value of 4.31 mWm −1  K −2 at 823 K in Zr 0.75 Ti 0.25 NiSn 0.98 Sb 0.02 , which was higher than Hf 0.25 Zr 0.25 Ti 0.5 NiSn 0.98 Sb 0.02 (4.01 mWm −1  K −2 at 773 K) in this study. However, the thermal conductivity of the Hf-free samples was significantly higher, by which the maximum dimensionless figure of merit was slightly lower (ZT max  = 0.92 in Zr 0.75 Ti 0.25 NiSn 0.98 Sb 0.02 at 873 K) than that of Hf 0.25 Zr 0.25 Ti 0.5 NiSn 0.98 Sb 0.02 (ZT max  = 1.03 at 873 K). The thermal conductivity was decomposed into lattice and electronic contributions, and the possible correlation with Ni off-stoichiometry is discussed.
ISSN:0361-5235
1543-186X
DOI:10.1007/s11664-021-08938-0