Publications

Crystallization behavior of vapor-deposited hexanitroazobenzene (HNAB) films

Knepper, Robert; Tappan, Alexander S.; Rodriguez, Marko A.; Alam, M.K.; Martin, Laura E.; Marquez, M.P.

Vapor-deposited hexanitroazobenzene (HNAB) has been shown to form an amorphous structure as-deposited that crystallizes over a period ranging from several hours to several weeks, depending on the ambient temperature. Raman spectroscopy and x-ray diffraction were used to identify three distinct phases during the crystallization process: the as-deposited amorphous structure, the HNAB-II crystal structure, and an as-yet unidentified crystal structure. Significant qualitative differences in the nucleation and growth of the crystalline phases were observed between 65°C and 75°C. While the same two polymorphs form in all cases, significant variation in the quantities of each phase was observed as a function of temperature. © 2012 American Institute of Physics.