Crystal Lab › Prototype structures › Orthorhombic
Mercury (II) Azide [Hg(N₃)₂]
Orthorhombic · space group Pca21 (No. 29) · Pearson oP28 · mineral: Mercury (II) Azide
Symmetry elements and Wyckoff positions (interactive)
Mercury (II) Azide [Hg(N₃)₂] in Pca21
SettingUnit cell
- Lattice constants
- a = 10.632 Å, b = 6.264 Å, c = 6.323 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 421.1 ų
- Atoms in the conventional cell
- 28 (Hg 4, N 24)
- Formula units Z
- 4
- Pearson symbol
- oP28 — orthorhombic, primitive lattice, 28 atoms per conventional cell
- Symmetry operations
- 4 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Hg1 | Hg | 4a | 4 | 0.0318 | 0.2388 | 0.2500 |
| N2 | N | 4a | 4 | 0.0820 | 0.9570 | 0.1060 |
| N3 | N | 4a | 4 | 0.1880 | 0.8930 | 0.1210 |
| N4 | N | 4a | 4 | 0.2840 | 0.8200 | 0.1120 |
| N5 | N | 4a | 4 | 0.9620 | 0.5290 | 0.3900 |
| N6 | N | 4a | 4 | 0.8830 | 0.6090 | 0.2800 |
| N7 | N | 4a | 4 | 0.8070 | 0.7000 | 0.1720 |
The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 28 atoms drawn above are these sites multiplied by all 4 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.
How to read the label
AB6_oP28_29_a_6a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP28, then the space-group number 29, then the Wyckoff letters occupied by each element in turn (Hg: 4a; N: 4a; N: 4a; N: 4a; N: 4a; N: 4a; N: 4a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: Mercury (II) Azide.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB6_oP28_29_a_6a-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.
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