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Enhancement of Thermoelectric Figure of Merit of p‐Type Nb 0.9 Ti 0.1 FeSb Half‐Heusler Compound by Nanostructuring
Author(s) -
Silpawilawan Wanthana,
Tanuslip Sora-at,
Ohishi Yuji,
Muta Hiroaki,
Kurosaki Ken
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.202000419
Subject(s) - spark plasma sintering , materials science , thermoelectric effect , thermal conductivity , phonon scattering , thermoelectric materials , figure of merit , condensed matter physics , melt spinning , phonon , grain boundary , sintering , metallurgy , optoelectronics , composite material , microstructure , thermodynamics , spinning , physics
Half‐Heusler compounds with 18 valence electron count show a large thermoelectric power factor. However, the thermal conductivity is high, so if the thermal conductivity can be reduced, the thermoelectric figure of merit zT can be enhanced. The key point to reduce the thermal conductivity is effective phonon scattering. Nanostructuring is a well‐known method of introducing phonon scattering centers by creating high‐density grain boundaries in nanoscale. Herein, NbFeSb, which is one of the best p‐type half‐Heusler compounds in thermoelectrics, is focused on. Nanostructured bulk Nb 0.9 Ti 0.1 FeSb is synthesized by melt spinning followed by spark plasma sintering. The cooling speed during melt spinning is changed to obtain nanostructures with different sizes. This study reveals that the zT at high temperatures is enhanced by nanostructuring. The nanostructured Nb 0.9 Ti 0.1 FeSb shows an ≈20% higher zT value at 1073 K than the non‐nanostructured one, mainly due to the effective reduction of the thermal conductivity.