Polycrystalline Parametrized as a Narrow-Band-Gap Semiconductor for Thermoelectric Performance
- Northwestern Univ., Evanston, IL (United States)
- Northwestern Univ., Evanston, IL (United States); Koc Univ., Istanbul (Turkey)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
The transition-metal pentatellurides HfTe5 and ZrTe5 have been studied for their exotic transport properties with much debate over the transport mechanism, band gap, and cause of the resistivity behavior, including a large low-temperature resistivity peak. Single crystals grown by the chemical-vapor-transport method have shown an n-p transition of the Seebeck coefficient at the same temperature as a peak in the resistivity. We show that behavior similar to that of single crystals can be observed in iodine-doped polycrystalline samples but that undoped polycrystalline samples exhibit drastically different properties: they are p type over the entire temperature range. Additionally, the thermal conductivity for polycrystalline samples is much lower, 1.5 Wm-1 K-1, than previously reported for single crystals. It is found that the polycrystalline ZrTe5 system can be modeled as a simple semiconductor with conduction and valence bands both contributing to transport, separated by a band gap of 20 meV. This model demonstrates to first order that a simple two-band model can explain the transition from n- to p-type behavior and the cause of the anomalous resistivity peak. Combined with the experimental data, the two-band model shows that carrier concentration variation is responsible for differences in behavior between samples. Using the two-band model, the thermoelectric performance at different doping levels is predicted, finding zT=0.2 and 0.1 for p and n type, respectively, at 300 K, and zT=0.23 and 0.32 for p and n type at 600 K. Given the reasonably high zT that is comparable in magnitude for both n and p type, a thermoelectric device with a single compound used for both legs is feasible.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC); National Renewable Energy Laboratory (NREL), Golden, CO (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC36-08GO28308; SC0001299; FG02-09ER46577; AC02-06CH11357
- OSTI ID:
- 1423194
- Alternate ID(s):
- OSTI ID: 1417937; OSTI ID: 1419961
- Report Number(s):
- NREL/JA-5K00-71006; PRAHB2; TRN: US1801719
- Journal Information:
- Physical Review Applied, Vol. 9, Issue 1; ISSN 2331-7019
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Thermal Conductivity of HfTe 5 : A Critical Revisit
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journal | November 2019 |
Magneto-thermoelectric characterization of a HfTe 5 micro-ribbon
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journal | August 2019 |
Log-periodic quantum magneto-oscillations and discrete-scale invariance in topological material HfTe5
|
journal | August 2019 |
Hot carrier dynamics and phonon anharmonicity of ZrTe 5 revealed with femtosecond transient optical spectroscopy
|
journal | January 2020 |
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