β-SrRh$_{2}$As$_{2}$ Structure: A2B2C_oF20_69_g_f_a-001
| Prototype | As$_{2}$Rh$_{2}$Sr |
| AFLOW prototype label | A2B2C_oF20_69_g_f_a-001 |
| ICSD | 417001 |
| Pearson symbol | oF20 |
| Space group number | 69 |
| Space group symbol | $Fmmm$ |
| AFLOW prototype command |
aflow --proto=A2B2C_oF20_69_g_f_a-001
--params=$a, \allowbreak b/a, \allowbreak c/a, \allowbreak x_{3}$ |
Other compounds with this structure
EuRh$_{2}$As$_{2}$
- SrRh$_{2}$As$_{2}$ is known to have two temperature-driven structural phase transitions (Zinth, 2012):
- Below 463K it is in the monoclinic $\alpha$–SrRh$_{2}$As$_{2}$ structure.
- In the range 463-555K it is in this orthorhombic $\beta$–SrRh$_{2}$As$_{2}$ structure.
- Above 555K $\gamma$–SrRh$_{2}$As$_{2}$ is in the tetragonal ThCr$_{2}$Si$_{2}$ structure.
- (Zinth, 2012) have incorrect Wyckoff symbols for the structure of $\beta$–SrRh$_{2}$As$_{2}$ in Table IV. We assume the actual positions are correct, and shift the position of the strontium atom to the origin.
- The ICSD entry is from the earlier work of (Hellman, 2007).
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&\frac{1}{2}b \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{3}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}b \,\mathbf{\hat{y}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (4a) | Sr I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{4} \, \mathbf{a}_{1}+\frac{1}{4} \, \mathbf{a}_{2}+\frac{1}{4} \, \mathbf{a}_{3}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{1}{4}b \,\mathbf{\hat{y}}+\frac{1}{4}c \,\mathbf{\hat{z}}$ | (8f) | Rh I |
| $\mathbf{B_{3}}$ | = | $\frac{3}{4} \, \mathbf{a}_{1}+\frac{3}{4} \, \mathbf{a}_{2}+\frac{3}{4} \, \mathbf{a}_{3}$ | = | $\frac{3}{4}a \,\mathbf{\hat{x}}+\frac{3}{4}b \,\mathbf{\hat{y}}+\frac{3}{4}c \,\mathbf{\hat{z}}$ | (8f) | Rh I |
| $\mathbf{B_{4}}$ | = | $- x_{3} \, \mathbf{a}_{1}+x_{3} \, \mathbf{a}_{2}+x_{3} \, \mathbf{a}_{3}$ | = | $a x_{3} \,\mathbf{\hat{x}}$ | (8g) | As I |
| $\mathbf{B_{5}}$ | = | $x_{3} \, \mathbf{a}_{1}- x_{3} \, \mathbf{a}_{2}- x_{3} \, \mathbf{a}_{3}$ | = | $- a x_{3} \,\mathbf{\hat{x}}$ | (8g) | As I |
References
- V. Zinth, V. Petricek, M. Dusek, and D. Johrendt, Structural phase transitions in SrRh$_{2}$As$_{2}$, Phys. Rev. B 85, 014109 (2012), doi:10.1103/PhysRevB.85.014109.
- A. Hellmann, A. Löhken, A. Wurth, and A. Mewis, New Arsenides with ThCr$_{2}$Si$_{2}$-type or Related Structures: The Compounds ARh$_{2}$As$_{2}$ (A: Eu, Sr, Ba) and BaZn$_{2}$As$_{2}$, Z. Naturforsch. B 62, 155–161 (2007), doi:10.1515/znb-2007-0203.
Prototype Generator
aflow --proto=A2B2C_oF20_69_g_f_a --params=$a,b/a,c/a,x_{3}$