Observation of Decomposition of Ammonium Dinitramide by Means of X-ray Diffraction

Decomposition of the inorganic oxidizer ammonium dinitramide (ADN) with the formation of ammonium nitrate (AN) during storage is a topic of high interest and widely studied in the last years. Generally, decomposition of energetic materials (EM) leads to altered physical properties and thus to unwanted changes in performance of the propellants and oxidizers. So, it is crucial to know for each EM safe storage conditions to prevent or to minimize decomposition. In the case of ADN, decomposition is influenced, among others, by moisture of the bulk material and the surrounding humidity, by temperature, exposure to ultraviolet radiation, impurities, and its free surface area to the environment. This article describes observations on the decomposition of a prepared ADN and formation of AN by means of long- term X-ray diffraction measurements. Rietveld refinement revealed two different polymorphs of the decomposition product AN. The results were compared to a proper stored ADN bulk material and X-ray diffraction measurements were supplemented by scanning electron microscopy.