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Ab initio simulation of $\mathrm{Ta_2O_5}$: A high symmetry ground state phase with application to interface calculation
- Source :
- Annalen der Physik 531, 1800524 (2019)
- Publication Year :
- 2018
-
Abstract
- We suggest a tetragonal $I4_1/amd$ phase ($\eta$-phase) as the ground state of $\mathrm{Ta_2O_5}$ at zero temperature, which is a high symmetry version of the triclinic $\gamma$-phase $\mathrm{Ta_2O_5}$ predicted by Yang and Kawazoe. Our calculation shows that $\gamma$-phase $\mathrm{Ta_2O_5}$ will automatically be transformed into the $\eta$-phase during structural relaxation. Phonon dispersion confirms that the $\eta$-phase is dynamically stable, while the high temperature $\alpha$-phase $\mathrm{Ta_2O_5}$, which also has the $I4_1/amd$ symmetry, is unstable at zero temperature. A thorough energy comparison of the $\beta_{AL}$, $\delta$, $\lambda$, $\mathrm{B}$, $\mathrm{L_{SR}}$, $\beta_R$, $Pm$, $Cmmm$, $\gamma$, $\eta$ and $\alpha$ phases of $\mathrm{Ta_2O_5}$ is carried out. The GGA-1/2 method is applied in calculating the electronic structure of various phases, where the $\eta$-phase demonstrates a 4.24 eV indirect band gap, close to experimental value. The high symmetry tetragonal phase together with computationally efficient GGA-1/2 method greatly facilitate the $ab\ initio$ simulation of $\mathrm{Ta_2O_5}$-based devices. As an example, we have explicitly shown the Ohmic contact nature between metal Ta and $\mathrm{Ta_2O_5}$ by calculating an interface model of $b.c.c.$ Ta and $\eta$-$\mathrm{Ta_2O_5}$, using GGA-1/2.<br />Comment: 27 pages, 8 figures
- Subjects :
- Condensed Matter - Materials Science
Subjects
Details
- Database :
- arXiv
- Journal :
- Annalen der Physik 531, 1800524 (2019)
- Publication Type :
- Report
- Accession number :
- edsarx.1812.04859
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1002/andp.201800524