$H5_{9}$ [Autunite Ca(UO$_{2}$)$_{2}$(PO$_{4}$)$_{2}\cdot 10 \frac{1}{2}$H$_{2}$O] Structure (Obsolete): AB2C2_tI10_139_a_d_e-003
| Prototype | Ca(H$_{2}$O)$_{10.5}$(PO$_{4}$)$_{2}$(UO$_{2}$)$_{2}$ |
| AFLOW prototype label | AB2C2_tI10_139_a_d_e-003 |
| Strukturbericht designation | $H5_{9}$ |
| Mineral name | autunite |
| ICSD | 33193 |
| Pearson symbol | tI10 |
| Space group number | 139 |
| Space group symbol | $I4/mmm$ |
| AFLOW prototype command |
aflow --proto=AB2C2_tI10_139_a_d_e-003
--params=$a, \allowbreak c/a, \allowbreak z_{3}$ |
- Autunite Ca(UO$_{2}$)$_{2}$(PO$_{4}$)$_{2}$·nH$_{2}$O, is found in three varieties:
- Naturally occurring Autunite, with $n \ge 10$,
- Partially dehydrated meta-autunite (I) ($6 \le n \le 10$).
- Further dehydration in the laboratory produces meta-autunite (II).
- (Beintema, 1938) proposed this structure for autunite, which (Herrmann, 1941) designated $H5_{9}$. This original tetragonal structure did not locate the oxygen atoms or the water molecules, although the ICSD entry does list atomic positions for the oxygen atoms which are not obviously obtained from the paper. Later determinations of this structure (Locock, 2003) located all the atoms in the crystal for $n = 11$, and found the structure to be orthorhombic.
- This form of autonite and Li$_{2}$CN$_{2}$ have the same AFLOW prototype label. They are generated by the same symmetry operations with different sets of parameters (
--params) specified in their corresponding CIF files.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&- \frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}- \frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}\\\mathbf{a_{3}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}- \frac{1}{2}c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (2a) | Ca 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) | P 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) | P I |
| $\mathbf{B_{4}}$ | = | $z_{3} \, \mathbf{a}_{1}+z_{3} \, \mathbf{a}_{2}$ | = | $c z_{3} \,\mathbf{\hat{z}}$ | (4e) | U I |
| $\mathbf{B_{5}}$ | = | $- z_{3} \, \mathbf{a}_{1}- z_{3} \, \mathbf{a}_{2}$ | = | $- c z_{3} \,\mathbf{\hat{z}}$ | (4e) | U I |
References
- J. Beintema, On the composition and the crystallography of autunite and the meta‐autunites, Rec. Trav. Chim. Pays-Bas 57, 155–175 (1938), doi:10.1002/recl.19380570206.
- A. J. Locock and P. C. Burns, The crystal structure of synthetic autunite, Ca[(UO$_{2}$)(PO$_{4}$)]$_{2}$(H$_{2}$O)$_{11}$, Am. Mineral. 88, 240–244 (2003), doi:10.2138/am-2003-0128.
Found in
- K. Herrmann, ed., Strukturbericht Band VI 1938 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1941).
Prototype Generator
aflow --proto=AB2C2_tI10_139_a_d_e --params=$a,c/a,z_{3}$