Effects of W alloying on the electronic structure, phase stability and thermoelectric power factor in epitaxial CrN thin films
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2023
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| author | Singh, Niraj Kumar Hjort, Victor Honnali, Sanath Kumar Gambino, Davide Febvrier, Arnaud le Ramanath, Ganpati Alling, Björn Eklund, Per |
| author_facet | Singh, Niraj Kumar Hjort, Victor Honnali, Sanath Kumar Gambino, Davide Febvrier, Arnaud le Ramanath, Ganpati Alling, Björn Eklund, Per |
| contents | CrN-based alloy thin films are of interest as thermoelectric materials for energy harvesting. Ab initio calculations show that dilute alloying of CrN with 3 at.% W substituting Cr, induce flat electronic bands and push the Fermi level EF into the conduction band, while retaining dispersive Cr 3d bands. These features are conducive for both high electrical conductivity σand high Seebeck coefficient α, and hence the thermoelectric power factor α^2σ. To investigate this possibility, epitaxial CrWxNz films were grown on c-plane sapphire by dc-magnetron sputtering. However, even films with the lowest W concentration (x = 0.03) in our study contained metallic h-Cr2N, which is not conducive for a high α. Nevertheless, the films exhibit a sizeable power factor of α^2σ~ 4.7 x 10-4 Wm-1K-2 due to high σ~ 700 Scm-1, and a moderate α~ -25 ~{^^^^00b5}V/K. Increasing h-Cr2N fractions in the 0.03 < x \le 0.19 range monotonically increases σ, but severely diminishes αleading to two orders of magnitude decrease in α^2σ. This trend continues with x > 0.19 due to W precipitation. These findings indicate that dilute W additions below its solubility limit in CrN is important for realizing high thermoelectric power factor in CrWxNz alloy films. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2311_02453 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Effects of W alloying on the electronic structure, phase stability and thermoelectric power factor in epitaxial CrN thin films Singh, Niraj Kumar Hjort, Victor Honnali, Sanath Kumar Gambino, Davide Febvrier, Arnaud le Ramanath, Ganpati Alling, Björn Eklund, Per Materials Science CrN-based alloy thin films are of interest as thermoelectric materials for energy harvesting. Ab initio calculations show that dilute alloying of CrN with 3 at.% W substituting Cr, induce flat electronic bands and push the Fermi level EF into the conduction band, while retaining dispersive Cr 3d bands. These features are conducive for both high electrical conductivity σand high Seebeck coefficient α, and hence the thermoelectric power factor α^2σ. To investigate this possibility, epitaxial CrWxNz films were grown on c-plane sapphire by dc-magnetron sputtering. However, even films with the lowest W concentration (x = 0.03) in our study contained metallic h-Cr2N, which is not conducive for a high α. Nevertheless, the films exhibit a sizeable power factor of α^2σ~ 4.7 x 10-4 Wm-1K-2 due to high σ~ 700 Scm-1, and a moderate α~ -25 ~{^^^^00b5}V/K. Increasing h-Cr2N fractions in the 0.03 < x \le 0.19 range monotonically increases σ, but severely diminishes αleading to two orders of magnitude decrease in α^2σ. This trend continues with x > 0.19 due to W precipitation. These findings indicate that dilute W additions below its solubility limit in CrN is important for realizing high thermoelectric power factor in CrWxNz alloy films. |
| title | Effects of W alloying on the electronic structure, phase stability and thermoelectric power factor in epitaxial CrN thin films |
| topic | Materials Science |
| url | https://arxiv.org/abs/2311.02453 |