### Thermoelectric properties of rocksalt ZnO from first-principles calculations

Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of its thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. Lastly, these results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.

- Publication Date:

- Grant/Contract Number:
- NA0001982

- Type:
- Accepted Manuscript

- Journal Name:
- Journal of Applied Physics

- Additional Journal Information:
- Journal Volume: 118; Journal Issue: 16; Journal ID: ISSN 0021-8979

- Publisher:
- American Institute of Physics (AIP)

- Research Org:
- Univ. of Nevada, Las Vegas, NV (United States)

- Sponsoring Org:
- USDOE National Nuclear Security Administration (NNSA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; II-VI semiconductors; phonons; thermal conductivity; high pressure; band gap

- OSTI Identifier:
- 1332447

- Alternate Identifier(s):
- OSTI ID: 1224327

```
Alvarado, Andrew, Attapattu, Jeevake, Zhang, Yi, and Chen, Changfeng.
```*Thermoelectric properties of rocksalt ZnO from first-principles calculations*. United States: N. p.,
Web. doi:10.1063/1.4934522.

```
Alvarado, Andrew, Attapattu, Jeevake, Zhang, Yi, & Chen, Changfeng.
```*Thermoelectric properties of rocksalt ZnO from first-principles calculations*. United States. doi:10.1063/1.4934522.

```
Alvarado, Andrew, Attapattu, Jeevake, Zhang, Yi, and Chen, Changfeng. 2015.
"Thermoelectric properties of rocksalt ZnO from first-principles calculations". United States.
doi:10.1063/1.4934522. https://www.osti.gov/servlets/purl/1332447.
```

```
@article{osti_1332447,
```

title = {Thermoelectric properties of rocksalt ZnO from first-principles calculations},

author = {Alvarado, Andrew and Attapattu, Jeevake and Zhang, Yi and Chen, Changfeng},

abstractNote = {Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of its thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. Lastly, these results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.},

doi = {10.1063/1.4934522},

journal = {Journal of Applied Physics},

number = 16,

volume = 118,

place = {United States},

year = {2015},

month = {10}

}