KCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$ Structure (12442-type superconductor): A4B2C2D4E_tI26_139_2e_e_d_g_a-001
| Prototype | As$_{4}$Ca$_{2}$F$_{2}$Fe$_{4}$K |
| AFLOW prototype label | A4B2C2D4E_tI26_139_2e_e_d_g_a-001 |
| ICSD | 239952 |
| Pearson symbol | tI26 |
| Space group number | 139 |
| Space group symbol | $I4/mmm$ |
| AFLOW prototype command |
aflow --proto=A4B2C2D4E_tI26_139_2e_e_d_g_a-001
--params=$a, \allowbreak c/a, \allowbreak z_{3}, \allowbreak z_{4}, \allowbreak z_{5}, \allowbreak z_{6}$ |
Other compounds with this structure
CsCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsCa$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsDy$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsDy$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsGd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsGd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsHo$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsHo$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsNd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsNd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsSm$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsSm$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, CsTb$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, CsTb$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KCa$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KDy$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KDy$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KGd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KGd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KHo$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KHo$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KNd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KNd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KSm$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KSm$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, KTb$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, KTb$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbCa$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbDy$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbDy$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbGd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbGd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbHo$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbHo$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbNd$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbNd$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbSm$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbSm$_{2}$Fe$_{4}$As$_{4}$O$_{2}$, RbTb$_{2}$Fe$_{4}$As$_{4}$F$_{2}$, RbTb$_{2}$Fe$_{4}$As$_{4}$O$_{2}$
- KCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$ is superconducting below 33K.
- The Wyckoff coordinates in Table I of (Wang, 2016) do not agree with the coordinates in the CIF in their supplementary material. The positions in the CIF agree with the positions shown in their Figure 1, so we use the CIF to generate the coordinates.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&- \frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}- \frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{3}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}- \frac{1}{2}c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (2a) | K I |
| $\mathbf{B_{2}}$ | = | $\frac{3}{4} \, \mathbf{a}_{1}+\frac{1}{4} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{4}c \,\mathbf{\hat{z}}$ | (4d) | F I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{4} \, \mathbf{a}_{1}+\frac{3}{4} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{4}c \,\mathbf{\hat{z}}$ | (4d) | F I |
| $\mathbf{B_{4}}$ | = | $z_{3} \, \mathbf{a}_{1}+z_{3} \, \mathbf{a}_{2}$ | = | $c z_{3} \,\mathbf{\hat{z}}$ | (4e) | As I |
| $\mathbf{B_{5}}$ | = | $- z_{3} \, \mathbf{a}_{1}- z_{3} \, \mathbf{a}_{2}$ | = | $- c z_{3} \,\mathbf{\hat{z}}$ | (4e) | As I |
| $\mathbf{B_{6}}$ | = | $z_{4} \, \mathbf{a}_{1}+z_{4} \, \mathbf{a}_{2}$ | = | $c z_{4} \,\mathbf{\hat{z}}$ | (4e) | As II |
| $\mathbf{B_{7}}$ | = | $- z_{4} \, \mathbf{a}_{1}- z_{4} \, \mathbf{a}_{2}$ | = | $- c z_{4} \,\mathbf{\hat{z}}$ | (4e) | As II |
| $\mathbf{B_{8}}$ | = | $z_{5} \, \mathbf{a}_{1}+z_{5} \, \mathbf{a}_{2}$ | = | $c z_{5} \,\mathbf{\hat{z}}$ | (4e) | Ca I |
| $\mathbf{B_{9}}$ | = | $- z_{5} \, \mathbf{a}_{1}- z_{5} \, \mathbf{a}_{2}$ | = | $- c z_{5} \,\mathbf{\hat{z}}$ | (4e) | Ca I |
| $\mathbf{B_{10}}$ | = | $\left(z_{6} + \frac{1}{2}\right) \, \mathbf{a}_{1}+z_{6} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}+c z_{6} \,\mathbf{\hat{z}}$ | (8g) | Fe I |
| $\mathbf{B_{11}}$ | = | $z_{6} \, \mathbf{a}_{1}+\left(z_{6} + \frac{1}{2}\right) \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+c z_{6} \,\mathbf{\hat{z}}$ | (8g) | Fe I |
| $\mathbf{B_{12}}$ | = | $- \left(z_{6} - \frac{1}{2}\right) \, \mathbf{a}_{1}- z_{6} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}- c z_{6} \,\mathbf{\hat{z}}$ | (8g) | Fe I |
| $\mathbf{B_{13}}$ | = | $- z_{6} \, \mathbf{a}_{1}- \left(z_{6} - \frac{1}{2}\right) \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}- c z_{6} \,\mathbf{\hat{z}}$ | (8g) | Fe I |
References
- Z.-C. Wang, C.-Y. He, S.-Q. Wu, Z.-T. Tang, Y. Liu, A. Ablimit, C.-M. Feng, and G.-H. Cao, Superconductivity in KCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$ with Separate Double Fe$_{2}$As$_{2}$ Layers, J. Am. Chem. Soc. 138, 7856–7859 (2016), doi:10.1021/jacs.6b04538.
Found in
- Z.-C. Wang, C.-Y. He, S.-Q. Wu, Z.-T. Tang, Y. Liu, and G.-H. Cao, Synthesis, Crystal Structure and Superconductivity in RbLn$_{2}$Fe$_{4}$As$_{4}$O$_{2}$ (Ln = Sm, Tb, Dy, and Ho), Chem. Mater. 29, 1805–1812 (2017), doi:10.1021/acs.chemmater.6b05458.
Prototype Generator
aflow --proto=A4B2C2D4E_tI26_139_2e_e_d_g_a --params=$a,c/a,z_{3},z_{4},z_{5},z_{6}$