NH$_{4}$NO$_{3}$ I ($G0_{8}$) Structure: AB_cP2_221_a_b-001
| Prototype | (NH$_{4}$)(NO$_{3}$) |
| AFLOW prototype label | AB_cP2_221_a_b-001 |
| Strukturbericht designation | $G0_{8}$ |
| Pearson symbol | cP2 |
| Space group number | 221 |
| Space group symbol | $Pm\overline{3}m$ |
| AFLOW prototype command |
aflow --proto=AB_cP2_221_a_b-001
--params=$a$ |
- Ammonium Nitrate exists in a variety of forms, (Hermann, 1937) depending on the temperature:
Phase Temperature °C Strukturbericht Page I 125 - 170 $G0_{8}$ AB_cP2_221_a_b-001 (this structure) II 84 - 125 $G0_{9}$ ABC3_tP10_100_b_a_bc-001 III 32 - 84 $G0_{10}$ ABC3_oP20_62_c_c_cd-002 IV -18 - 32 $G0_{11}$ A4B2C3_oP18_59_ef_ab_af-001 V $< -18$ A4B2C3_tP72_77_8d_ab2c2d_6d2-001
- In the $G0_{8}$ structure, both the NH$_{4}$ and NO$_{3}$ radicals rotate freely about their centers of mass (Kracek, 1931). The two radicals sit on the same sites as atoms in the CsCl ($B2$) structure.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&a \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $0$ | = | $0$ | (1a) | NH I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}+\frac{1}{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+\frac{1}{2}a \,\mathbf{\hat{z}}$ | (1b) | NO I |
References
- F. C. Kracek, S. B. Hendricks, and E. Posnjak, Group Rotation in Soid Ammonium and Calcium Nitrates, Nature 128, 410–411 (1931), doi:10.1038/128410b0.
- S. B. Hendricks, E. Posnjak, and F. C. Kracek, Molecular Rotation in the Solid State. The Variation of the Crystal Structure of Ammonium Nitrate with Temperature, J. Am. Chem. Soc. 54, 2766–2786 (1932), doi:10.1021/ja01346a020.
Found in
- C. Hermann, O. Lohrmann, and H. Philipp, eds., Strukturbericht Band II 1928-1932 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1937).
First cited in
- 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, Comp. Mat. Sci. 199, 110450 (2021). (doi=10.1016/j.commatsci.2021.110450)
Geometry files
Prototype Generator
aflow --proto=AB_cP2_221_a_b --params=$a$