PREPARATION OF GAMMA-IRON ULTRAFINE PARTICLES USING A TRANSVERSELY EXCITED ATMOSPHERIC CO2-LASER

gamma-Iron ultrafine particles which are stable at room temperature ha ve been prepared in a high yield of maximum 90% by the SF6-sensitized infrared photodecomposition of Fe(CO)5 using a transversely excited at mospheric (TEA) CO2 laser. The obtained gamma-iron particles are isotr opic in shape, having an uniform size of 6.5-8.5 nm with a mean size o f 7.6 nm and fcc structure, and are paramagnetic at 1.8-295 K The para magnetic fcc gamma-iron particles begin to transform into ferromagneti c bcc alpha-iron above 473 K with almost complete conversion to alpha- iron at 653-693 K.