Lead azide crystals which usually explode at temperatures below 320°have minimum explosion temperatures of 500°when dropped into molten alkali halides and 620°when dropped into molten alkali nitrates. Calculations indicate that the high explosion temperatures observed in molten salts may be due to the greatly improved conditions for heat transfer to the surroundings. In alkali nitrate melts lead oxide is formed instead of catalytically acting lead metal which may be the cause for the further increased explosion temperature.
The thermal decompositions of undoped and doped potassium azide melts were studied. The decomposition rates were increased orders of magnitudes by doping with certain transition metal salts. First rapid initial reactions occurred which can be represented by the equation M2+¡mpunty + 2Na~-*• M°+ 3N2. Some metals precipitated immediately after their formation. Others remained dissolved for certain periods, the lengths of which were, temperature dependent. Dissolved metals were without influence while precipitated metals catalyzed the decomposition. With group VIII metals the same activation energy was observed with precipitated as well as massive metals. Group I-B metals showed a lower activation energy when precipitated which was attributed to a decrease in the temperature at which vacancies can be formed in the d band by thermal activation.
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