IR laser photodeposition of a-Fe/Si films developing nanograins of ferrisilicate, iron disilicide and rare hexagonal iron upon annealing

Abstract

IR laser-induced gas-phase photolysis of Fe(CO)(5)-SiH(4) mixtures occurs as SiH(4)-photosensitized decomposition of Fe(CO)(5) is accelerated by products of this decomposition and it results in deposition of amorphous Si/Fe nanocomposite films. Analyses of the deposited and subsequently annealed solid films were made by FTIR, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and electron microscopy. The deposited films are amorphous, contain crystalline nanostructures of iron silicide FeSi(2) and undergo atmospheric oxidation in topmost layers to iron oxide and hydrogenated silicon oxide. Upon annealing they develop nanocrystalline structures of ferrisilicate, Fe(1.6)SiO(4), carbon-encaged iron disilicide, FeSi(2), and very rare hexagonal (high-pressure) Fe surviving at ambient conditions. The mechanism of formation of these nanostructures is discussed in terms of gas-phase and solid-phase reactions.

Laser-induced ablative amorphization of montmorillonite

“…Similar laser-induced processes were, in fact, recently described by us [28,39,40,29] for laser deposition of rare metal nanostructures stabilized in polymer and carbonaceous amorphous phase.…”

Laser photochemical deposition of magnetite nanograins in a-Fe/C/O composite: High-pressure metal oxide polymorph surviving ambient conditions

“…The single-pulseinduced processes were accomplished through laser ablation of Ag or Ga and simultaneous dielectric breakdown in hydrocarbon leading to formation of stabilizing carbonaceous phase [40,41], or through UV laser gas-phase silane-iron pentacarbonyl cophotolysis leading to photodeposition of Fe in amorphous Fe/Si phase [42].…”