Magnetic field effect on chemical compositions of spherical Fe/Co fine particles synthesized from a gaseous mixture of iron pentacarbonyl and cobalt tricarbonyl nitrosyl

Abstract

Under UV light irradiation on a gaseous mixture of Fe(CO)5 and Co(CO)3NO, both the crystalline deposits with sizes of ∼5 and ∼18μm and the spherical particles with a mean diameter of 0.3μm were produced. From FT-IR spectra and SEM–EDS analysis, it was suggested that the chemical structure of the crystalline deposits was the one of Fe2(CO)9 being modified by involving Fe(CO)Co bond. By decreasing a partial pressure of Fe(CO)5 to 0.5Torr in the gaseous mixture, only the spherical aerosol particles could be produced. Chemical composition of the particles was rich in Co species. From the disappearance of bridging CO band in the FT-IR spectra of the particles and the appearance of CO bands coordinated to a metal atom, Fe atom in Fe(CO)4 was suggested to be coordinated by the O atom in bridging CO bond in Co(CO)Co structure and/or in α-diketone structure which was formed from two CO groups in dicobalt species. Chemical compositions of the crystalline deposits and the spherical particles were influenced differently by the application of a magnetic field. Atomic ratio of Fe to Co atom decreased in the crystalline deposits whereas it increased in the spherical particles with increasing magnetic field up to 5T. Linearly aggregated particles (i.e., particle wires) as long as 30μm were produced on the front side of a glass plate placed at the bottom of the irradiation cell.