Simulation of Internal Defects in TKX-50 Crystals

Area of Science:

• Materials Science
• Computational Chemistry
• Crystallography

Background:

• 1,1'-Dihydroxy-5,5'-bi-tetrazolium dihydroxylamine salt (TKX-50) is a high-energy, low-sensitivity explosive with significant application potential.
• Direct synthesis of TKX-50 results in irregular crystal morphology and large aspect ratios, negatively impacting its sensitivity and limiting large-scale use.
• Internal crystal defects are critical to the performance and sensitivity of TKX-50, making their study theoretically significant and practically valuable.

Purpose of the Study:

• To investigate the microscopic properties of TKX-50 crystals.
• To establish a correlation between microscopic parameters and macroscopic susceptibility.
• To understand the impact of specific crystal defects on TKX-50's energetic properties.

Main Methods:

• Development of scaled TKX-50 crystal models incorporating three types of defects: vacancy, dislocation, and doping.
• Application of molecular dynamics simulations to analyze the behavior of these defective crystal models.
• Evaluation of defect influence on key properties: initiation bond length, density, bonding diatomic interaction energy, and cohesive energy density.

Main Results:

• Simulations demonstrated that increased initiator bond length and defect percentage correlate with higher crystal sensitivities.
• Defects were shown to activate the initiator's N-N bond, reduce bond-linked diatomic energy, cohesive energy density, and overall density.
• A preliminary link was established between microscopic model parameters (related to defects) and macroscopic susceptibility.

Conclusions:

• Crystal defects significantly influence the sensitivity of TKX-50 by altering its fundamental energetic properties.
• Molecular dynamics simulations provide a valuable method for predicting the sensitivity of energetic materials based on their microstructural characteristics.
• The findings offer guidance for experimental design and can be extended to the study of other energetic materials.