Preparation of γ-Iron Ultrafine Particles Using a Transversely Excited Atmospheric CO2 Laser

Abstract
γ-Iron ultrafine particles which are stable at room temperature have been prepared in a high yield of maximum 90% by the SF6-sensitized infrared photodecomposition of Fe(CO)5 using a transversely excited atmospheric (TEA) CO2 laser. The obtained γ-iron particles are isotropic in shape, having an uniform size of 6.5–8.5 nm with a mean size of 7.6 nm and fcc structure, and are paramagnetic at 1.8–295 K The paramagnetic fcc γ-iron particles begin to transform into ferromagnetic bcc α-iron above 473 K with almost complete conversion to α-iron at 653–693 K.