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Rotational defects in cyclotrimethylene trinitramine (RDX) crystals
1Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
The Journal of Chemical Physics
|February 12, 2015
Summary
This study identifies novel rotational point defects in cyclotrimethylene trinitramine (RDX) crystals. These defects have lower formation energies than vacancies and are crucial for understanding RDX
Area of Science:
- Materials Science
- Crystallography
- Physical Chemistry
Background:
- Cyclotrimethylene trinitramine (RDX) exists as an orthorhombic α-phase under ambient conditions.
- Point defects like vacancies and interstitials are common in crystals.
- Molecular crystals, such as RDX, exhibit unique defects due to molecular distortions.
Purpose of the Study:
- To describe and characterize novel rotational point defects in RDX crystals.
- To compute the energy barriers for the formation and annealing of these rotational defects.
- To investigate the role of these defects in RDX crystal properties and behavior.
Main Methods:
- Atomistic modeling was employed to calculate energetic barriers.
- Defect formation and annealing energies were computed.
- Identification of defects within dislocation cores was performed.
Main Results:
- A set of rotational defects, involving rotated and puckered molecules, were identified in RDX.
- The formation energy of rotational defects is lower than that of vacancies.
- These rotational defects were found in the cores of dislocations in RDX.
Conclusions:
- Rotational defects are significant point defects in RDX crystals.
- Their concentration is expected to increase with plastic deformation.
- These defects influence phonon scattering and dislocation-mediated plastic deformation in RDX.
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