High-pressure (200GPa) H$_{3}$S Structure: A3B_cI8_229_b_a-001
| Prototype | H$_{3}$S |
| AFLOW prototype label | A3B_cI8_229_b_a-001 |
| ICSD | 291502 |
| Pearson symbol | cI8 |
| Space group number | 229 |
| Space group symbol | $Im\overline{3}m$ |
| AFLOW prototype command |
aflow --proto=A3B_cI8_229_b_a-001
--params=$a$ |
Other compounds with this structure
La$_{2}$O$_{3}$, Nd$_{2}$O$_{3}$
- (Duan, 2014) predicted that this structure of H$_{3}$S would be a conventional superconductor at temperatures above 191 K and a pressure of 200 GPa. (Drozdov, 2015) found a superconductor in the hydrogen-sulfur system at 203 K and pressure near 200 GPa. (Bernstein, 2015) showed that this structure is the ground state of the H–S system near 200 GPa. Both La$_{2}$O$_{3}$ and Nd$_{2}$O$_{3}$ can form in this structure under ambient conditions, but in both cases the oxygen atoms occupy only 50% of the (6b) Wyckoff positions.
- We have used the fact that all vectors of the form $(\pm a/2 \hat{x} \pm a/2 \hat{y} \pm a/2 \hat{z})$ are primitive vectors of the body-centered cubic lattice to simplify the positions of some atoms in both lattice and Cartesian coordinates.
- The oxides with this structure have a large number of defects, with the oxygen (6b) sites only partially filled.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&- \frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}a \,\mathbf{\hat{z}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}- \frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}a \,\mathbf{\hat{z}}\\\mathbf{a_{3}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}- \frac{1}{2}a \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (2a) | S I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}$ | (6b) | H I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}$ | (6b) | H I |
| $\mathbf{B_{4}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}$ | = | $\frac{1}{2}a \,\mathbf{\hat{z}}$ | (6b) | H I |
References
- D. Duan, Y. Liu, F. Tian, D. Li, X. Huang, Z. Zhao, H. Yu, B. Liu, W. Tian, and T. Cui, Pressure-induced metallization of dense (H$_2$S)$_2$H$_2$ with high-T$_c$ superconductivity, Sci. Rep. 4, 6968 (2014), doi:10.1038/srep06968.
- A. P. Drozdov, M. I. Eremets, I. A. Troyan, V. Ksenofontov, and S. I. Shylin, Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system, Nature 525, 73–76 (2015), doi:10.1038/nature14964.
- N. Bernstein, C. S. Hellberg, M. D. Johannes, I. I. Mazin, and M. J. Mehl, What superconducts in sulfur hydrides under pressure and why, Phys. Rev. B 91, 060511(R) (2015), doi:10.1103/PhysRevB.91.060511.
Prototype Generator
aflow --proto=A3B_cI8_229_b_a --params=$a$