α-Po ($A_{h}$, simple cubic) Structure: A_cP1_221_a-001
| Prototype | Po |
| AFLOW prototype label | A_cP1_221_a-001 |
| Strukturbericht designation | $A_{h}$ |
| ICSD | 655031 |
| CCDC | 1765802 |
| Pearson symbol | cP1 |
| Space group number | 221 |
| Space group symbol | $Pm\overline{3}m$ |
| AFLOW prototype command |
aflow --proto=A_cP1_221_a-001
--params=$a$ |
Other compounds with this structure
Nd$_{0.5}$Te$_{0.5}$
- Solid polonium exists in two phases: cubic $\alpha$–Po ($A_{h}$) (this structure) is the ground state and rhombohedral $\beta$–Po ($A_{l}$) (Donohue, 1974). There is a large amount of hysteresis observed in the transition, which occurs at 54$^\circ$C for $\alpha \rightarrow \beta$ and 18$^\circ$ for $\beta \rightarrow \alpha$.
- This is a simple cubic lattice. Polonium is the only element known with this ground state. Originally Po was assigned Strukturbericht designation $A19$, which is now considered to be incorrect. (Donohue, 1982, 390)
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&a \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (1a) | Po I |
References
- W. H. Beamer and C. R. Maxwel, The Crystal Structure of Polonium, J. Chem. Phys. 14, 569 (1946), doi:10.1063/1.1724201.
- C. Gottfried, ed., Strukturbericht Band IV 1936 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1938).
Found in
- J. Donohue, The Structures of the Elements (Robert E. Krieger Publishing Company, New York, 1974).
First cited in
- M. J. Mehl, D. Hicks, C. Toher, O. Levy, R. M. Hanson, G. L. W. Hart, and S. Curtarolo, The AFLOW Library of Crystallographic Prototypes: Part 1, Comp. Mat. Sci. 136, S1-S828 (2017). (doi=10.1016/j.commatsci.2017.01.017)
Geometry files
Prototype Generator
aflow --proto=A_cP1_221_a --params=$a$