High-Temperature UP$_{2}$ Structure: A2B_tP6_129_ac_c-002
Other compounds with this structure
AmS$_{2}$, AmSe$_{2}$, AmTe$_{2}$, CeS$_{2}$, CeSe$_{2}$, CeTe$_{2}$, CmS$_{2}$, CmSe$_{2}$, CmTe$_{2}$, DyS$_{2}$, DySe$_{2}$, DyTe$_{2}$, ErS$_{2}$, ErSe$_{2}$, ErTe$_{2}$, GdS$_{2}$, GdSe$_{2}$, GdTe$_{2}$, HfSb$_{2}$, HoS$_{2}$, HoSe$_{2}$, HoTe$_{2}$, LaS$_{2}$, LaSe$_{2}$, LaTe$_{2}$, LuS$_{2}$, LuSe$_{2}$, LuTe$_{2}$, NdSe$_{2}$, NdTe$_{2}$, NpAs$_{2}$, NpTe$_{2}$, PaAs$_{2}$, PaP$_{2}$, PaSb$_{2}$, PrSe$_{2}$, PrTe$_{2}$, PuS$_{2}$, PuSe$_{2}$, PuTe$_{2}$, SmSe$_{2}$, SmTe$_{2}$, TbS$_{2}$, TbTe$_{2}$, ThAs$_{2}$, ThBi$_{2}$, ThSb$_{2}$, TmS$_{2}$, TmSe$_{2}$, TmTe$_{2}$, UAs$_{2}$, UBi$_{2}$, UP$_{2}$, USb$_{2}$, UTe$_{2}$, YbS$_{2}$, YbSe$_{2}$, YbTe$_{2}$, YS$_{2}$, YSe$_{2}$, YTe$_{2}$
- At temperatures below 83$^\circ$C UP$_{2}$ transforms into its low-temperature structure (Gerward, 1990).
- The atomic positions are not explicitly given in (Gerward, 1990), so we take them from the ICSD entry.
- Cu$_{2}$Sb ($C38$), UP$_{2}$, and LaSe$_{1.85}$ have similar AFLOW prototype labels, A2B_tP6_129_ac_c for the first two and AB2_tP6_129_c_ac for the third. They are generated by the same symmetry operations with different sets of parameters (
--params) specified in their corresponding CIF files. - We consider all of these to be binary forms of Matlockite ($E0_{1}$)/PrOI.
- We somewhat arbitrarily assign
- Structures with c/a $<$ 2 to the Cu$_{2}$Sb prototype,
- Structures with 2 $<$ c/a $<$ 3 to the UP$_{2}$ prototype, and
- Structures with c/a ≈ 4 to the LaSe$_{1.85}$ prototype.
- The ICSD distinction between Cu$_{2}$Sb and UP$_{2}$ is not the same as ours, and they often assign binary compounds to the ternary prototypes.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $\frac{3}{4} \, \mathbf{a}_{1}+\frac{1}{4} \, \mathbf{a}_{2}$ | = | $\frac{3}{4}a \,\mathbf{\hat{x}}+\frac{1}{4}a \,\mathbf{\hat{y}}$ | (2a) | P I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{4} \, \mathbf{a}_{1}+\frac{3}{4} \, \mathbf{a}_{2}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{3}{4}a \,\mathbf{\hat{y}}$ | (2a) | P I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{4} \, \mathbf{a}_{1}+\frac{1}{4} \, \mathbf{a}_{2}+z_{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{1}{4}a \,\mathbf{\hat{y}}+c z_{2} \,\mathbf{\hat{z}}$ | (2c) | P II |
| $\mathbf{B_{4}}$ | = | $\frac{3}{4} \, \mathbf{a}_{1}+\frac{3}{4} \, \mathbf{a}_{2}- z_{2} \, \mathbf{a}_{3}$ | = | $\frac{3}{4}a \,\mathbf{\hat{x}}+\frac{3}{4}a \,\mathbf{\hat{y}}- c z_{2} \,\mathbf{\hat{z}}$ | (2c) | P II |
| $\mathbf{B_{5}}$ | = | $\frac{1}{4} \, \mathbf{a}_{1}+\frac{1}{4} \, \mathbf{a}_{2}+z_{3} \, \mathbf{a}_{3}$ | = | $\frac{1}{4}a \,\mathbf{\hat{x}}+\frac{1}{4}a \,\mathbf{\hat{y}}+c z_{3} \,\mathbf{\hat{z}}$ | (2c) | U I |
| $\mathbf{B_{6}}$ | = | $\frac{3}{4} \, \mathbf{a}_{1}+\frac{3}{4} \, \mathbf{a}_{2}- z_{3} \, \mathbf{a}_{3}$ | = | $\frac{3}{4}a \,\mathbf{\hat{x}}+\frac{3}{4}a \,\mathbf{\hat{y}}- c z_{3} \,\mathbf{\hat{z}}$ | (2c) | U I |
References
- L. Gerward, J. S. Olsen, U. Benedict, S. Dabos-Seignon, and H. Luo, Crystal structures of UP$_2$, UAs$_2$, UAsS and UAsSe in the pressure range up to 60 GPa, High T - High P 22, 523–532 (1990).
Found in
- Inorganic Crystal Structure Database}. Entry 648244 (UP$_{2$).
First cited in
- N. Anderson, M. J. Mehl, H. Eckert, S. Divilov, X. Campilongo, S. Curtarolo, The AFLOW Library of Crystallographic Prototypes: Part 5. Submitted to Computational Materials Science (2026).
Geometry files
Prototype Generator
aflow --proto=A2B_tP6_129_ac_c --params=$a,c/a,z_{2},z_{3}$