Reactive characterization of anhydrous iodine (v) oxide (I2O5) with aluminum: amorphous versus crystalline microstructures

Abstract

Iodine pentoxide (I2O5) is typically synthesized by dehydration of iodic acid such that the produced material inherently includes hydrated iodic acid species that facilitate further water absorption when exposed to ambient environments. This is a detrimental property for I2O5 powder used in energetic systems. A dry-approach for synthesizing I2O5 with either crystalline (nano C I2O5) or amorphous (nano A I2O5) structure was used for this study and compared to the commercially available material. This synthesis approach enabled isolation of the microstructure as a variable to better understand water absorption behavior of I2O5 and associated reactivity. Material characterization included BET, SEM, TEM, and XRD as well as equilibrium analyses using DSC and TGA along with flame speeds. Results show that nano C I2O5 reacts less with atmospheric water and has a more anhydrous behavior than the crystalline I2O5 powder commercially available. The nano A I2O5 also produced a distinct pre-ignition reaction (PIR) and evidence for smaller PIRs are shown for all mixtures of Al with I2O5. These properties along with increased specific surface area of the nano C I2O5 and nano A I2O increased reactivity and enhanced combustion with Al when compared with commercial I2O5.