Characterization of Crystal Microstructure Based on Small Angle X-ray Scattering (SAXS) Technique

Area of Science:

• Materials Science
• Crystallography
• Analytical Chemistry

Background:

• Small-angle X-ray scattering (SAXS) is crucial for material microstructure analysis.
• Crystal surface effects can introduce deviations in SAXS characterization of internal microstructure.
• Accurate internal defect signal detection is vital for understanding material properties.

Purpose of the Study:

• To develop a method to mitigate crystal surface effects in SAXS.
• To accurately characterize the internal microstructure of Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals.
• To validate the method using CL-20 crystals and compare results with PDDA.

Main Methods:

• Soaking HMX crystals in an electron density matching solution (GPL-107 perfluoropolyether - PFPE).
• Performing SAXS measurements on soaked and unsoaked samples.
• Comparing scattering intensities, specific surface areas, and volume fractions.
• Calculating fitting density and comparing with Particle Density Distribution Analyzer (PDDA) results.

Main Results:

• Soaking significantly reduced absolute scattering intensity, specific surface, and volume fraction, indicating successful mitigation of surface effects.
• GPL-107 PFPE solution provided the best results for HMX, a finding consistent with CL-20 crystals.
• Calculated fitting densities closely matched experimental PDDA results.

Conclusions:

• Soaking in an appropriate matching solution effectively eliminates crystal surface effects in SAXS.
• This method enables accurate internal microstructure characterization of energetic materials.
• The validated approach offers a reliable technique for microstructural analysis.