Strontium azide, decomposition

Moore, Thermal Decomposition of Strontium Azide , Nature 205, 1209-11 (1965)... 

SrN6 (c). Wohler and Martin1 measured the heat of decomposition of strontium azide to be 49.0. 

Thermal decompositions of barium and strontium azides, preirradiated with 1 MeV gamma rays, were conducted by Prout and Moore [78,79]. With dehydrated barium azide a total gamma dose of 20 Mrad (2.24 X 10 R) eliminated the induction period and increased the acceleration of the decomposition. A somewhat greater effect was evidenced with strontium azide. Avrami et al. [80] subjected barium azide to Co gamma radiation to exposure levels up to 1 XIO R (Table XIII). Differential thermal analyses (Figure 16) showed a steady decomposition of the sample, and after 1 X 10 R exposure (W hr at room temperature), infrared analysis indicated that the residue was in the form of barium carbonate. 

Most of the studies conducted on azides irradiated with X-rays have involved the changes caused in the subsequent thermal decomposition of the samples. Erofeev and Sviridov [90] studied the effects of moisture and aging on barium azide. An increased decomposition rate was noted with strontium azide preirradiated with X-rays and decomposed at 126°C [91]. Zakharov and coworkers... 

UV irradiation of other azides was conducted by Muller and Brous on sodium azide [99], by Garner and Maggs on barium and strontium azides [113], by Mott on metal azides [114], and by Boldyrev and Skorik on silver and barium azides [115]. Sodium, strontium, and barium azides are decomposed by UV light at room temperature, and their thermal decomposition is accelerated by preirradiation. Boldyrev et al. found that irradiating silver azide with UV light or X-rays at the instant of decomposition had no effect on the rate of its thermal decomposition. 

Early studies made in conjunction with thermal decomposition experiments [185] showed that for barium and strontium azide, preirradiation with UV light shortened the time elapsed before a previously selected pressure was achieved during thermal decomposition. It was observed that the UV light increased the number of centers at which small aggregates of barium metal or barium nitride could form during the subsequent thermal decomposition. Prolonged illumination was also observed to produce nuclei directly. In contrast, preirradiation of potassium azide with UV light had no effect on its subsequent thermal decomposition [210]. 

Dining the preparation of cellular rubber by thermal decomposition of calcium, strontium or barium azides, various additives were necessary to prevent explosive decomposition of the azide in the blended mixture. 

The explosive properties of sodium, calcium, strontium and barium azides have been investigated at the Chemisch-Technische Reichsanstalt [135]. These azides differ markedly from lead, silver and cupric azides in that they show none of the properties of primary explosives. All three may be ignited by a spark, a glowing wire or the flame of blackpowder. Calcium azide bums most rapidly and has distinctly marked explosive properties. Larger quantities of it may explode when ignited in a closed tin, while strontium and barium merely bum violently. Calcium azide detonates under the influence of a detonating cap. The sodium azide does not decompose in these conditions. The other azides show weak decomposition under the influence of a standard (No. 3) detonator. Their most important properties are tabulated below. 

This formation of spontaneously ignitible strontium and barium has been reported by Tiede, He also mentions the decomposition of calcium and lithium azide under the same conditions, but remarks only that lithium azide is rather explosive on heating. 

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