Studies on the thermal decomposition of alkali metal azides and perchlorates

Abstract

The thesis embodies investigations on the mechanism of the thermal decomposition of the alkali metal azides and perchlorates. A lot of work has been done on the thermal decomposition of these metastable materials. However, these studies were carried out at relatively high temperatures wherein complexities either due to melting of the crystal lattice or due to interaction of the decomposition products with the parent compound could arise. It would not be justifiable, under such circumstances, to interpret the results from such high?temperature studies in terms of the solid?state theories of nucleation and nucleus growth. Hence, to obtain a true picture of a solid?phase decomposition, studies should be carried out at fairly low temperatures. Moreover, these investigations would clearly indicate the role played by the various types of imperfections in determining the kinetics and the mechanism of decomposition. The present programme consists of a study of the thermal decomposition of sodium azide, potassium azide and cesium azide in the alkali?metal azide series, and sodium perchlorate and potassium perchlorate among the alkali?metal perchlorates. The importance of the metallic azides stems from their explosive character. Although the alkali metal azides are relatively stable compounds, it is generally believed that the mechanism of thermal decomposition is the same as that of the heavy?metal azides. An inherent advantage with the alkali metal azides is that their decomposition can be studied over a wide range of temperatures due to their greater thermal stability. This would, in turn, enable us to have a deeper understanding of the mechanism of the thermal decomposition of the metallic azides. A survey of the work done to date on the thermal decomposition of the alkali metal azides reveals that certain discrepancies exist in the literature as regards their nature of decomposition.