NH$_{4}$NO$_{3}$ II ($G0_{9}$) Structure: ABC3_tP10_100_b_a_bc-001
| Prototype | N(NH$_{4}$)O$_{3}$ |
| AFLOW prototype label | ABC3_tP10_100_b_a_bc-001 |
| Strukturbericht designation | $G0_{9}$ |
| ICSD | none |
| Pearson symbol | tP10 |
| Space group number | 100 |
| Space group symbol | $P4bm$ |
| AFLOW prototype command |
aflow --proto=ABC3_tP10_100_b_a_bc-001
--params=$a, \allowbreak c/a, \allowbreak z_{1}, \allowbreak z_{2}, \allowbreak z_{3}, \allowbreak x_{4}, \allowbreak z_{4}$ |
- 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 II 84 - 125 $G0_{9}$ ABC3_tP10_100_b_a_bc (this structure) 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
- Data for this structure was taken at 60°C.
- The positions of the hydrogen atoms were not determined. The isolated nitrogen atoms in this structure's visualization are surrounded by four hydrogen atoms in an approximately tetrahedral arrangement. It is likely that the NH$_{4}$ radicals are free to rotate (Kracek, 1937).
- Both (Shinnaka, 1956) and (Hermann, 1937) state that the available X-ray diffraction data supports a space group of either $P4bm$ #100 or $P\overline{4}2_{1}m$ #113. The atomic positions found by Shinnaka agree with space group $P4bm$.
- (Shinnaka, 1956) states that the NO$_{3}$ nitrate groups are rotating, but this rotation
is almost bound in two orientations (in opposite directions).
He then gives two possible orientations for the nitrate. We present the first orientation here. The second orientation is obtained by taking $z_{3} \rightarrow - z_{3}$ and $z_{4} \rightarrow - z_{4}$. - Another way of presenting this information would be to add a second nitrate group to the primitive cell, and set the occupation of all the atoms in the nitrates at 50%. This would give a structure in space group $P4/mbm$ #127, which might be useful as a pictorial representation but does not correctly represent the physics of the crystal, as the nitrogen and oxygen atoms in an individual nitrate radical must remain together.
- The N-O distances in this structure are about 10% smaller than the distances found in the other phases of NH$_{4}$NO$_{3}$. This suggests that the structure should be reevaluated.
\[ \begin{array}{ccc}
\mathbf{a_{1}}&=&a \,\mathbf{\hat{x}}\\\mathbf{a_{2}}&=&a \,\mathbf{\hat{y}}\\\mathbf{a_{3}}&=&c \,\mathbf{\hat{z}}
\end{array}\]
Basis vectors
| Lattice coordinates | Cartesian coordinates | Wyckoff position | Atom type | |||
|---|---|---|---|---|---|---|
| $\mathbf{B_{1}}$ | = | $z_{1} \, \mathbf{a}_{3}$ | = | $c z_{1} \,\mathbf{\hat{z}}$ | (2a) | NH I |
| $\mathbf{B_{2}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+\frac{1}{2} \, \mathbf{a}_{2}+z_{1} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+\frac{1}{2}a \,\mathbf{\hat{y}}+c z_{1} \,\mathbf{\hat{z}}$ | (2a) | NH I |
| $\mathbf{B_{3}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+z_{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+c z_{2} \,\mathbf{\hat{z}}$ | (2b) | N I |
| $\mathbf{B_{4}}$ | = | $\frac{1}{2} \, \mathbf{a}_{2}+z_{2} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}+c z_{2} \,\mathbf{\hat{z}}$ | (2b) | N I |
| $\mathbf{B_{5}}$ | = | $\frac{1}{2} \, \mathbf{a}_{1}+z_{3} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{x}}+c z_{3} \,\mathbf{\hat{z}}$ | (2b) | O I |
| $\mathbf{B_{6}}$ | = | $\frac{1}{2} \, \mathbf{a}_{2}+z_{3} \, \mathbf{a}_{3}$ | = | $\frac{1}{2}a \,\mathbf{\hat{y}}+c z_{3} \,\mathbf{\hat{z}}$ | (2b) | O I |
| $\mathbf{B_{7}}$ | = | $x_{4} \, \mathbf{a}_{1}+\left(x_{4} + \frac{1}{2}\right) \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $a x_{4} \,\mathbf{\hat{x}}+a \left(x_{4} + \frac{1}{2}\right) \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (4c) | O II |
| $\mathbf{B_{8}}$ | = | $- x_{4} \, \mathbf{a}_{1}- \left(x_{4} - \frac{1}{2}\right) \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $- a x_{4} \,\mathbf{\hat{x}}- a \left(x_{4} - \frac{1}{2}\right) \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (4c) | O II |
| $\mathbf{B_{9}}$ | = | $- \left(x_{4} - \frac{1}{2}\right) \, \mathbf{a}_{1}+x_{4} \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $- a \left(x_{4} - \frac{1}{2}\right) \,\mathbf{\hat{x}}+a x_{4} \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (4c) | O II |
| $\mathbf{B_{10}}$ | = | $\left(x_{4} + \frac{1}{2}\right) \, \mathbf{a}_{1}- x_{4} \, \mathbf{a}_{2}+z_{4} \, \mathbf{a}_{3}$ | = | $a \left(x_{4} + \frac{1}{2}\right) \,\mathbf{\hat{x}}- a x_{4} \,\mathbf{\hat{y}}+c z_{4} \,\mathbf{\hat{z}}$ | (4c) | O II |
References
- Y. Shinnaka, On the Metastable Transition and the Crystal Structure of Ammonium Nitrate (Tetragonal Modification), J. Phys. Soc. Jpn. 11, 393–396 (1956), doi:10.1143/JPSJ.11.393.
- C. Hermann, O. Lohrmann, and H. Philipp, eds., Strukturbericht Band II 1928-1932 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1937).
- 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.
Found in
- C. S. Choi, J. E. Mapes, and E. Prince, The structure of ammonium nitrate (IV), Acta Crystallogr. Sect. B 28, 1357–1361 (1972), doi:10.1107/S0567740872004303.
Prototype Generator
aflow --proto=ABC3_tP10_100_b_a_bc --params=$a,c/a,z_{1},z_{2},z_{3},x_{4},z_{4}$