Hexagonal WO$_{3}$ Structure: A3B_hP12_191_gl_f-001
| Prototype | O$_{3}$W |
| AFLOW prototype label | A3B_hP12_191_gl_f-001 |
| ICSD | 32001 |
| Pearson symbol | hP12 |
| Space group number | 191 |
| Space group symbol | $P6/mmm$ |
| AFLOW prototype command |
aflow --proto=A3B_hP12_191_gl_f-001
--params=$a, \allowbreak c/a, \allowbreak x_{3}$ |
- All stable phases of WO$_{3}$ are distortions of the cubic $\alpha$–ReO$_{3}$ ($D0_{9}$) phase. Based on (Woodward, 1997 and Vogt, 1999), the known stable phases and their approximate temperature ranges are:
- Woodward notes that
The transition temperatures display large hysteresis effects and universal agreement is not found in the literature.
- In addition, several other structures have been proposed and/or found:
- The original $D0_{10}$ structure (Bräkken, 1931; Hermann, 1937), superseded by $\delta$–WO$_{3}$
- The original $\beta$–WO$_{3}$ (Salje, 1977)
- Hexagonal WO$_{3}$, presumably metastable, found by (Gerand, 1979) while dehydrating WO$_{3}$·H$_{2}$O (this structure)
- (Gerand, 1979) determined the structure of hexagonal WO$_{3}$ by X-ray diffraction of powdered samples. They found evidence of super-reflection, indicating that the unit cell should be doubled along the $c$-axis, but were unable to determine the shift in atomic positions for the double unit cell. We report what they called the
half-cell
structure.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}- \frac{\sqrt{3}}{2}a \,\mathbf{\hat{y}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{\sqrt{3}}{2}a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}- \frac{\sqrt{3}}{4}a \,\mathbf{\hat{y}}$ | (3f) | W I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{2}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{\sqrt{3}}{4}a \,\mathbf{\hat{y}}$ | (3f) | W I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}$ | (3f) | W I |
| $\mathbf{B_{4}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}- \frac{\sqrt{3}}{4}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}$ | (3g) | O I |
| $\mathbf{B_{5}}$ | = | $\frac{1}{2} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{\sqrt{3}}{4}a \,\mathbf{\hat{y}}+\frac{1}{2}c \,\mathbf{\hat{z}}$ | (3g) | O I |
| $\mathbf{B_{6}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}c \,\mathbf{\hat{z}}$ | (3g) | O I |
| $\mathbf{B_{7}}$ | = | $x_{3} \, \mathbf{a}_{1}+2 x_{3} \, \mathbf{a}_{2}$ | = | $\frac{3}{2}a x_{3} \,\mathbf{\hat{x}}+\frac{\sqrt{3}}{2}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
| $\mathbf{B_{8}}$ | = | $- 2 x_{3} \, \mathbf{a}_{1}- x_{3} \, \mathbf{a}_{2}$ | = | $- \frac{3}{2}a x_{3} \,\mathbf{\hat{x}}+\frac{\sqrt{3}}{2}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
| $\mathbf{B_{9}}$ | = | $x_{3} \, \mathbf{a}_{1}- x_{3} \, \mathbf{a}_{2}$ | = | $- \sqrt{3}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
| $\mathbf{B_{10}}$ | = | $- x_{3} \, \mathbf{a}_{1}- 2 x_{3} \, \mathbf{a}_{2}$ | = | $- \frac{3}{2}a x_{3} \,\mathbf{\hat{x}}- \frac{\sqrt{3}}{2}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
| $\mathbf{B_{11}}$ | = | $2 x_{3} \, \mathbf{a}_{1}+x_{3} \, \mathbf{a}_{2}$ | = | $\frac{3}{2}a x_{3} \,\mathbf{\hat{x}}- \frac{\sqrt{3}}{2}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
| $\mathbf{B_{12}}$ | = | $- x_{3} \, \mathbf{a}_{1}+x_{3} \, \mathbf{a}_{2}$ | = | $\sqrt{3}a x_{3} \,\mathbf{\hat{y}}$ | (6l) | O II |
References
- P. M. Woodward, A. W. Sleight, and T. Vogt, Ferroelectric Tungsten Trioxide, J. Solid State Chem. 131, 9–17 (1997), doi:10.1006/jssc.1997.7268.
- T. Vogt, P. M. Woodward, and B. A. Hunter, The High-Temperature Phases of WO$_{3}$, J. Solid State Chem. 144, 209–215 (1999), doi:10.1006/jssc.1999.8173.
- R. Diehl, G. Brandt, and E. Salje, The Crystal Structure of Triclinic WO$_{3}$, Acta Crystallogr. Sect. B 34, 1105–1111 (1978), doi:10.1107/S0567740878005014.
- H. Bräkken, Die Kristallstrukturen der Trioxyde von Chrom, Molybdän und Wolfram, Z. Kristallogr. 78, 484–488 (1931), doi:10.1524/zkri.1931.78.1.484.
- C. Hermann, O. Lohrmann, and H. Philipp, eds., Strukturbericht Band II 1928-1932 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1937).
- E. Salje, The Orthorhombic Phase of WO$_{3}$, Acta Crystallogr. Sect. B 33, 574–577 (1977), doi:10.1107/S0567740877004130.
- B. Gerand, G. Nowogrocki, J. Guenot, and M. Figlarz, Structural study of a new hexagonal form of tungsten trioxide, J. Solid State Chem. 29, 429–434 (1979), doi:10.1016/0022-4596(79)90199-3.
Found in
- P. Villars and L. Calvert, Pearson's Handbook of Crystallographic Data for Intermetallic Phases (ASM International, Materials Park, OH, 1991), 2nd edn.
Prototype Generator
aflow --proto=A3B_hP12_191_gl_f --params=$a,c/a,x_{3}$