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Long-term stability of phase-separated half-Heusler compounds.
1Institute for Inorganic and Analytical Chemistry, Johannes Gutenberg University Mainz, Staudingerweg 9, 55128 Mainz, Germany. balke@uni-mainz.de.
Physical Chemistry Chemical Physics : PCCP
|October 22, 2015
Summary
This study shows that phase-separated Half-Heusler (HH) compounds maintain excellent thermoelectric properties, including high Seebeck coefficients and low thermal conductivity, after extensive thermal cycling. These findings highlight their potential for industrial applications.
Area of Science:
- Materials Science
- Solid State Physics
- Thermoelectrics
Background:
- Half-Heusler (HH) compounds are promising thermoelectric materials with figures of merit up to 1.5.
- Long-term stability is crucial for industrial applications of thermoelectric devices.
Purpose of the Study:
- To investigate the long-term stability of n- and p-type Half-Heusler (HH) materials.
- To evaluate the impact of thermal cycling on the microstructure and thermoelectric properties of HH compounds.
Main Methods:
- Investigated HH materials based on the Ti0.3Zr0.35Hf0.35NiSn system.
- Subjected materials to 500 cycles (1700 h) between 373 K and 873 K.
- Analyzed changes in microstructure and thermoelectric properties (Seebeck coefficient, thermal conductivity).
Main Results:
- Both n- and p-type HH compounds exhibited a maximum Seebeck coefficient of |α|≈ 210 μV K(-1).
- Phase separation into two HH phases was observed, which remained stable.
- The dendritic microstructure demonstrated temperature resistance, with marginal changes upon cycling.
- Low thermal conductivity values (κ < 4 W m(-1) K(-1)) were maintained.
Conclusions:
- Phase-separated HH compounds are stable and suitable for long-term thermoelectric applications.
- The maintained thermoelectric properties suggest potential for enhanced efficiencies beyond current benchmarks.
- These cost-effective materials show promise for industrial thermoelectric device development.
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