The Flame Emission of Indium from a Pyrotechnical View

Abstract

Until today, all blue-colored light-generating pyrotechnics are still based on copper and a halogen-source providing the blue-emitting species copper(I) chloride, copper(I) bromide or copper(I) iodide. The use of indium as a potential halogen-free blue light emitter in modern pyrotechnics is described. Therefore, metallic indium was introduced as both fuel and colorant in various pyrotechnical formulations including guanidine nitrate or potassium nitrate as oxidizing agent as well as magnesium, hexamethylentetramine and 5-amino-1H-tetrazole as fuel. The effect of incandescence was examined by applying different magnesium contents within the mixtures. Emission spectra and occurring emission lines of indium-based pyrotechnical compositions were recorded and evaluated for the first time. Since the expected blue flame color could not be completely achieved, the emission of indium was discussed from an academic point of view.