Aerosol synthesis of phase pure iodine/iodic biocide microparticles
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High iodine containing oxides are of interest as biocidal components in energetic applications requiring fast exothermic reactions with metallic fuels. Aerosol techniques offer a convenient route and potentially direct route for preparation of small particles with high purity, and are a method proven to be amenable and economical to scale-up. Here, we demonstrate the synthesis of various iodine oxide/iodic acid microparticles by a direct one-step aerosol method from iodic acid. By varying temperature and humidity, we produced near phase pure d-HIO3, HI3O8, and I2O5 as determined by X-ray diffraction. d-HIO3, a previously unknown phase, was confirmed in this work. In addition, scanning electron microscopy was used to examine the morphology and size of those prepared iodine oxide/iodic acid particles and the results show that all particles have an irregularly spherical shape. Thermogravimetric/differential scanning calorimetry measurement results show that HIO3 dehydrates endothermically to HI3O8, and then to I2O. I2O5 decomposes to I2 and O2.
I. INTRODUCTION
In recent years, the interest in developing new energetic materials with biocidal capabilities1,2 has drawn increased attention.3–13 The motivation for this is based on evidence that conventional energetic materials, which employ a thermal neutralization mechanism, are not sufficiently efficient.14 Laboratory studies have demonstrated that the addition of a biocidal component can significantly enhance neutralization through a synergistic mechanism.15–20 Therefore, it has been proposed that simultaneously delivering a rapid thermal pulse with a remnant biocidal agent would prolong the exposure time and improve the inactivation process.21 Both halogens and silver-containing energetic materials have been explored22–24 with the halogens offering the most promise due to their excellent biocidal properties.25 Various methods have been used for incorporating halogens into energetic materials. One approach is through directly introducing halogens into the system and the other is by incorporating halogens into the oxidizers.25,26 Thus, iodine-rich compounds that can release HI or I2 are the ideal candidates for biocidal energetics.27 Iodine (V) oxide, as one of the iodine-containing oxides with ;76% iodine mass fraction, has been recently studied as an oxidizer with aluminum fuel. 28 In this case, various metals (primarily aluminum) are mixed with I 2 O5 to form a thermite system whose combustion
Contributing Editor: Gary L. Messing a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.6
properties were studied.29–32 The first paper concerning the reactivity between aluminum and I2O5 was published by Ivanov et al. in 1980 in which a global reaction mechanism between iodine gas and fuels was proposed29 and confirmed in a later work.32 I2O5 has received considerable interest because it is an extremely aggressive oxidizer with aluminum with reported propagation velocities up to ;2000 m/s for loose ball-milled nanoaluminum and nano-scaled I2O5
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