skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

This content will become publicly available on February 14, 2020

Title: Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine

Abstract

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 β–δ 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, γ–δ. 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 overmore » 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. Finally, our work supports the idea that virtual melting may be a more generally applicable mechanism for structural phase transitions in organic crystalline solids.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [2];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Iowa State Univ., Ames, IA (United States). Dept. of Aerospace Engineering, Mechanical Engineering, and Material Science and Engineering
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1499348
Report Number(s):
LA-UR-17-30452
Journal ID: ISSN 0021-9606
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 150; Journal Issue: 6; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Bowlan, Pamela Renee, Henson, Bryan Fayne, Smilowitz, Laura Beth, Levitas, Valery, Suvorova, Natalya Alexandra, and Oschwald, David M. Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. United States: N. p., 2019. Web. doi:10.1063/1.5080010.
Bowlan, Pamela Renee, Henson, Bryan Fayne, Smilowitz, Laura Beth, Levitas, Valery, Suvorova, Natalya Alexandra, & Oschwald, David M. Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. United States. doi:10.1063/1.5080010.
Bowlan, Pamela Renee, Henson, Bryan Fayne, Smilowitz, Laura Beth, Levitas, Valery, Suvorova, Natalya Alexandra, and Oschwald, David M. Thu . "Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine". United States. doi:10.1063/1.5080010.
@article{osti_1499348,
title = {Kinetics of the γ–δ phase transition in energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine},
author = {Bowlan, Pamela Renee and Henson, Bryan Fayne and Smilowitz, Laura Beth and Levitas, Valery and Suvorova, Natalya Alexandra and Oschwald, David M.},
abstractNote = {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 β–δ 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, γ–δ. 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. Finally, our work supports the idea that virtual melting may be a more generally applicable mechanism for structural phase transitions in organic crystalline solids.},
doi = {10.1063/1.5080010},
journal = {Journal of Chemical Physics},
number = 6,
volume = 150,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on February 14, 2020
Publisher's Version of Record

Save / Share:

Works referenced in this record:

The ?�? phase transition in the energetic nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine: Thermodynamics
journal, August 2002

  • Henson, B. F.; Smilowitz, L.; Asay, B. W.
  • The Journal of Chemical Physics, Vol. 117, Issue 8, p. 3780-3788
  • DOI: 10.1063/1.1495398

The ?�? phase transition in the energetic nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine: Kinetics
journal, August 2002

  • Smilowitz, L.; Henson, B. F.; Asay, B. W.
  • The Journal of Chemical Physics, Vol. 117, Issue 8, p. 3789-3798
  • DOI: 10.1063/1.1495399

Origins and Applications of London Dispersion Forces and Hamaker Constants in Ceramics
journal, September 2000