Reaction kinetics and combustion dynamics of I₄O₉ and aluminum mixtures

Tetraiodine nonoxide (I₄O₉) has been synthesized using a dry approach that combines elemental oxygen and iodine without the introduction of hydrated species. The synthesis approach inhibits the topochemical effect promoting rapid hydration when exposed to the relative humidity of ambient air. This stable, amorphous, nano-particle material was analyzed using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) and showed an exothermic energy release at low temperature (i.e., 180 °C) for the transformation of I₄O₉ into I₂O₅. This additional exothermic energy release contributes to an increase in overall reactivity of I₄O₉ when dry mixed with nano-aluminum (Al) powder, resulting in a minimum of 150% increase in flame speed compared to Al + I₂O₅. This study shows that as an oxidizer, I₄O₉ has more reactive potential than other forms of iodine(V) oxide when combined with Al, especially if I₄O₉ can be passivated to inhibit absorption of water from its surrounding environment.