Abstract
Half-Heusler alloys have been one of the benchmark high temperature thermoelectric materials owing to their thermal stability and promising figure of merit ZT. Simonson et al. early showed that small amounts of vanadium doped in Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change with the increased density of states near the Fermi level. We herein report a systematic study on the role of vanadium (V), niobium (Nb), and tantalum (Ta) as prospective resonant dopants in enhancing the ZT of n-type half-Heusler alloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase the Seebeck coefficient in the temperature range 300-1000 K, consistent with a resonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as evident by the systematic decrease in electrical resistivity and Seebeck coefficient. The combination of enhanced Seebeck coefficient due to the presence of V resonant states and the reduced thermal conductivity has led to a state-of-the-art ZT of 1.3 near 850 K in n-type (Hf0.6Zr0.4)0.99V0.01NiSn0.995Sb0.005 alloys.
Highlights
Thermoelectric materials can directly convert heat to electricity and vice versa, making thermoelectrics an important component of the renewable energy technology
The performance of thermoelectric material is measured by the dimensionless figure of merit ZT, ZT = (S2σ/κ)T, where σ is the electrical conductivity, S is the Seebeck coefficient, κ is the total thermal conductivity
Among the state-of-the-art thermoelectric materials, the RNiSn (R = Hf, Zr and Ti) half-Heusler (HH) phases have been noted by their thermal stability,[1,2] scalability, and potential for large power output,[3,4,5,6] and the combination of high Seebeck coefficient and low thermal conductivity.[7,8,9,10,11,12]
Summary
Thermoelectric materials can directly convert heat to electricity and vice versa, making thermoelectrics an important component of the renewable energy technology. High thermoelectric figure of merit by resonant dopant in half-Heusler alloys
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
