This review explores strategies for stabilizing the polymorphic phases of ammonium nitrate (AN), a promising chlorine-free oxidizer for green propellant systems. Despite its eco-friendly decomposition products, AN’s widespread use is limited by phase transitions near ambient temperature, which cause volumetric expansion, reduced density, and mechanical instability. To address these issues, researchers have investigated various additives such as potassium salts, metal oxides, organic compounds, polymers, and metal-organic frameworks (MOFs and ZIFs). These materials inhibit AN’s undesirable transitions and improve thermal performance. Recent innovations include hybrid systems and nanostructured additives that combine stability with enhanced energetic output.
Mousaviaza et al. (Sun,) studied this question.