Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine Bowlan, P. Henson, B. F. Smilowitz, L. Levitas, Valery Suvorova, N. Levitas, Valery Oschwald, D.
dc.contributor.department Aerospace Engineering
dc.contributor.department Ames Laboratory
dc.contributor.department Mechanical Engineering
dc.contributor.department Materials Science and Engineering 2019-03-13T08:21:38.000 2020-06-29T22:45:32Z 2020-06-29T22:45:32Z Tue Jan 01 00:00:00 UTC 2019 2019-01-01
dc.description.abstract <p>The solid, secondary explosive nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7 or HMX has four different stable polymorphs which have different molecular conformations, crystalline structures, and densities, making structural phase transitions between these nontrivial. Previous studies of the kinetics of the <em>β</em>–<em>δ</em> HMX structural transition found this to happen by a nucleation and growth mechanism, where growth was governed by the heat of fusion, or melting, even though the phase transition temperature is more than 100 K below the melting point. A theory known as virtual melting could easily justify this since the large volume difference in the two phases creates a strain at their interface that can lower the melting point to the phase transition temperature through a relaxation of the elastic energy. To learn more about structural phase transitions in organic crystalline solids and virtual melting, here we use time-resolved X-ray diffraction to study another structural phase transition in HMX, <em>γ</em>–<em>δ</em>. Again, second order kinetics are observed which fit to the same nucleation and growth model associated with growth by melting even though the volume change in this transition is too small to lower the melting point by interfacial strain. To account for this, we present a more general model illustrating that melting over a very thin layer at the interface between the two phases reduces the total interfacial energy and is therefore thermodynamically favorable and can drive the structural phase transition in the absence of large volume changes. Our work supports the idea that virtual melting may be a more generally applicable mechanism for structural phase transitions in organic crystalline solids.</p>
dc.description.comments <p>This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Bowlan, P., B. F. Henson, L. Smilowitz, V. I. Levitas, N. Suvorova, and D. Oschwald. "Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine." <em>The Journal of Chemical Physics</em> 150, no. 6 (2019): 064705, and may be found at DOI: <a href="" target="_blank">10.1063/1.5080010</a>. Posted with permission.</p>
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dc.identifier archive/
dc.identifier.articleid 1140
dc.identifier.contextkey 13901209
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath aere_pubs/139
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 20:03:50 UTC 2022
dc.source.uri 10.1063/1.5080010
dc.subject.disciplines Biological and Chemical Physics
dc.subject.disciplines Materials Chemistry
dc.title Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine
dc.type article
dc.type.genre article
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