Investigation of tetrazole- and bistetrazole-based lithium salts as colorants in environmentally friendly pyrotechnics

Abstract

ABSTRACT Due to the harmful effects of chlorinated combustion products and strontium in currently used red-burning pyrotechnics on human health and the environment, new substitutes have to be found. A promising alternative could be using lithium-salts. While it is a literature-known problem that the generation of a lithium-based red flame color is a challenging task due to the diverse requirements of the Li(0) color species, a promising alternative could be using lithium-heterocycle salts. In this context, nitrogen-rich lithium tetrazole and bistetrazole salts, namely, lithium tetrazolate, lithium 5-aminotetrazolate, dilithium 5,5’-bistetrazolate dihydrate and dilithium 5,5’-bis(tetrazolate-1-oxide) have been investigated as potential replacements. To evaluate the performance of the salts a variety of mixtures were prepared and their pyrotechnic parameters were analyzed. Furthermore, application-specific pyrotechnic clusters and parachute flares were produced and these were also tested for burning time, dominant wavelength, spectral purity and luminous intensity. Observations on the use of lithiated nitrogen-rich salts in pyrotechnic mixtures showed a red color impression, indicating the potential of these mixtures. Further research opportunities can be pursued by refining nitrogen-rich compounds.