Evolution of the oxidation of ultrasmall α-Fe particles

Abstract Ultrafine iron particles, prepared by an evaporation technique, have been studied by the use of Mossbauer spectroscopy as a function of time of exposure to air. The passivation layer is found to contain poorly crystallized, cubic iron oxide. Measurements in large external magnetic fields at 5 K showed that the oxide had a noncolinear spin structure, in contrast to ferrimagnetic bulk oxides. This is presumably related to the small particle size.