Post-perovskite (MgSiO$_{3}$) Structure: AB3C_oC20_63_c_cf_a-001
| Prototype | MgO$_{3}$Si |
| AFLOW prototype label | AB3C_oC20_63_c_cf_a-001 |
| ICSD | 158959 |
| Pearson symbol | oC20 |
| Space group number | 63 |
| Space group symbol | $Cmcm$ |
| AFLOW prototype command |
aflow --proto=AB3C_oC20_63_c_cf_a-001
--params=$a, \allowbreak b/a, \allowbreak c/a, \allowbreak y_{2}, \allowbreak y_{3}, \allowbreak y_{4}, \allowbreak z_{4}$ |
Other compounds with this structure
AlNHf$_{3}$, AlNTi$_{3}$, AlNZr$_{3}$, AsCCr$_{3}$, AsCV$_{3}$, CaBrIn$_{3}$, CaIrO$_{3}$, CaPtO$_{3}$, CaRhO$_{3}$, CeYbSe$_{3}$, FeNaF$_{3}$, GeCV$_{3}$, GeNV$_{3}$, LaYbS$_{3}$, LaYbSe$_{3}$, LuNdSe$_{3}$, LuPrSe$_{3}$, MgGeO$_{3}$, NaIrO$_{3}$, NaMgF$_{3}$, NaNiF$_{3}$, NdYbSe$_{3}$, NiOZr$_{3}$, PCV$_{3}$, PNCr$_{3}$, PNV$_{3}$, POZr$_{3}$, PbTlI$_{3}$, PrYbSe$_{3}$, ScUS$_{3}$
- This structure was determined by a combination of x-ray diffraction measurements and atomistic simulations of MgSiO$_{3}$ at a pressure of 121 GPa and a temperature of 300 K. This approximates the conditions at the Earth's core-mantle boundary.
- An earlier version of this page (Hicks, 2021) inadvertently switched the positions of the silicon and magnesium atoms, producing an incorrect structure with the AFLOW label AB3C_oC20_63_a_cf_c. Searches for that structure will redirect here. We apologize for the error.
- The ground state structure of MgSiO$_{3}$ is enstatite ($S4_{3}$).
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}- \frac{1}{2}b \,\mathbf{\hat{y}}\\\mathbf{a_{2}}&=&\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}b \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (4a) | Si I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}c \,\mathbf{\hat{z}}$ | (4a) | Si I |
| $\mathbf{B_{3}}$ | = | $- y_{2} \, \mathbf{a}_{1}+y_{2} \, \mathbf{a}_{2}+\frac{1}{4} \, \mathbf{a}_{3}$ | = | $b y_{2} \,\mathbf{\hat{y}}+\frac{1}{4}c \,\mathbf{\hat{z}}$ | (4c) | Mg I |
| $\mathbf{B_{4}}$ | = | $y_{2} \, \mathbf{a}_{1}- y_{2} \, \mathbf{a}_{2}+\frac{3}{4} \, \mathbf{a}_{3}$ | = | $- b y_{2} \,\mathbf{\hat{y}}+\frac{3}{4}c \,\mathbf{\hat{z}}$ | (4c) | Mg I |
| $\mathbf{B_{5}}$ | = | $- y_{3} \, \mathbf{a}_{1}+y_{3} \, \mathbf{a}_{2}+\frac{1}{4} \, \mathbf{a}_{3}$ | = | $b y_{3} \,\mathbf{\hat{y}}+\frac{1}{4}c \,\mathbf{\hat{z}}$ | (4c) | O I |
| $\mathbf{B_{6}}$ | = | $y_{3} \, \mathbf{a}_{1}- y_{3} \, \mathbf{a}_{2}+\frac{3}{4} \, \mathbf{a}_{3}$ | = | $- b y_{3} \,\mathbf{\hat{y}}+\frac{3}{4}c \,\mathbf{\hat{z}}$ | (4c) | O I |
| $\mathbf{B_{7}}$ | = | $- y_{4} \, \mathbf{a}_{1}+y_{4} \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $b y_{4} \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (8f) | O II |
| $\mathbf{B_{8}}$ | = | $y_{4} \, \mathbf{a}_{1}- y_{4} \, \mathbf{a}_{2}+\left(z_{4} + \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $- b y_{4} \,\mathbf{\hat{y}}+c \left(z_{4} + \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (8f) | O II |
| $\mathbf{B_{9}}$ | = | $- y_{4} \, \mathbf{a}_{1}+y_{4} \, \mathbf{a}_{2}- \left(z_{4} - \frac{1}{2}\right) \, \mathbf{a}_{3}$ | = | $b y_{4} \,\mathbf{\hat{y}}- c \left(z_{4} - \frac{1}{2}\right) \,\mathbf{\hat{z}}$ | (8f) | O II |
| $\mathbf{B_{10}}$ | = | $y_{4} \, \mathbf{a}_{1}- y_{4} \, \mathbf{a}_{2}- z_{4} \, \mathbf{a}_{3}$ | = | $- b y_{4} \,\mathbf{\hat{y}}- c z_{4} \,\mathbf{\hat{z}}$ | (8f) | O II |
References
- M. Murakami, K. Hirose, K. Kawamura, N. Sata, and Y. Ohishi, Post-Perovskite Phase Transition in MgSiO$_{3}$, Science 304, 855–858 (2005), doi:10.1126/science.1095932.
- D. Hicks, M. J.Mehl, M. Esters, C. Oses, O. Levy, G. L. W. Hart, C. Toher, and S. Curtarolo, The AFLOW Library of Crystallographic Prototypes: Part 3, Comput. Mater. Sci. 199, 110450 (2021), doi:10.1016/j.commatsci.2021.110450.
Prototype Generator
aflow --proto=AB3C_oC20_63_c_cf_a --params=$a,b/a,c/a,y_{2},y_{3},y_{4},z_{4}$