Journal of Applied Crystallography

Volume 37, Part 5 (October 2004)

J. Appl. Cryst. (2004). 37, 808-814 [doi:10.1107/S0021889804017832]

Energetic materials: variable-temperature crystal structures of - and -HNIW polymorphs

N. B. Bolotina, M. J. Hardie, R. L. Speer Jr and A. A. Pinkerton

Abstract: Crystals of [bold gamma] - and [bold epsilon] -hexanitrohexaazaisowurtzitane (- and -HNIW, space group P2₁/n for both crystals) have been investigated in the 100-298 K temperature range using single-crystal X-ray diffraction techniques. Temperature-dependent changes of their crystal lattices have been evaluated from the second-rank thermal expansion tensors. Both lattices undergo anisotropic thermal expansion, that of [bold gamma] -HNIW being more anisotropic than that of the [bold epsilon] phase. Comparison with previously reported predictions from molecular dynamics calculations indicates significant differences. Although there are many short (less than van der Waals) intermolecular interactions in both polymorphs, there is no obvious relationship between the short distances and the difference in thermal expansion behavior. Non-linear temperature dependence of the atomic displacement parameters is indicative of anharmonicity of the crystal mean field potential.

Online 11 September 2004


	Structure factor file (CIF format) (179.0 kbytes) Contains datablock 298gHNIW

	Structure factor file (CIF format) (177.1 kbytes) Contains datablock 250gHNIW

	Structure factor file (CIF format) (176.6 kbytes) Contains datablock 200gHNIW

	Structure factor file (CIF format) (175.3 kbytes) Contains datablock 150gHNIW

	Structure factor file (CIF format) (174.7 kbytes) Contains datablock 100gHNIW

	Structure factor file (CIF format) (183.1 kbytes) Contains datablock 298eHNIW

	Structure factor file (CIF format) (182.0 kbytes) Contains datablock 250eHNIW

	Structure factor file (CIF format) (180.5 kbytes) Contains datablock 200eHNIW

	Structure factor file (CIF format) (179.9 kbytes) Contains datablock 150eHNIW

	Structure factor file (CIF format) (179.0 kbytes) Contains datablock 100eHNIW

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