Diagnostics of carbon-encapsulated iron nanoparticles by laser heating

Abstract

In this study the laser-induced incandescence (LII) diagnostics has been applied for sizing of carbon-encapsulated iron nanoparticles (CEINs). The carbon covered iron nanoparticles were synthesized by shock waves pyrolysis of the mixtures of Fe(CO)5 with C2H2 or C6H6 diluted with argon. Iron nanoparticles were formed in the shock tube behind incident shock waves at the temperatures of 700–1000 K. The pyrolysis of hydrocarbons behind reflected shock waves at the temperatures of 1400–2000 K resulted in formation of carbon shell over iron nanoparticles. At the end of the CEINs formation process, particles were heated by one pulse of Nd:YAG laser operated at wavelength 1064 nm with fluences varied in the range 70– 800 mJ/cm2 to collect LII signals. The LII model, which had been used previously for iron and carbon nanoparticles separately, was updated for carbon-encapsulated iron nanoparticles. Additionally, the nanoparticle samples were investigated by a transmission electron microscope (TEM). The iron core size and carbon shell thickness were measured by statistical treatment of microphotographs. The comparison of TEM and LII particle sizing results is discussed.