Submicron-Sized Gamma-HMX: 1. Preparation and Initial Characterization

As part of our ongoing nanotechnology research effort, we have developed a novel method for the preparation of submicron-sized HMX (sm-HMX) by a simple fast-cooling technique. Surface structure analysis of the sm-HMX by field emission scanning electron microscopy reveals particles that are oblong in shape with average width of ∼ 300 nm and length of ∼ 1–2 µm. Raman spectroscopic features in the 200–2000 cm−1 range and high-intensity powder neutron diffraction were used to determine the crystallographic polymorph of the sm-HMX. Comparison of the Raman spectrum and the neutron powder diffraction pattern of sm-HMX to literature data show that sm-HMX is the gamma polymorph. The Raman data also illustrate that the polymorphic purity of the gamma sm-HMX produced by our method is greater than 99%.