Magnetic properties of a novel iron carbide film, Fe/sub 7/C/sub 3x/ formed in a glow discharge

Plasma enhanced chemical vapor deposition offers considerable promise for producing unique metal and ceramic structures. Notable features of this deposition technique include low temperature processing, ease of reproducibility, the preparation of unusual phases, the production of either amorphous or oriented crystalline films, and the alteration of film properties by using different process conditions and post production thermal treatment. The iron-carbon-oxygen system has been used to deposit a number of unique films, some of which may have useful magnetic properties. This paper describes magnetic and Mössbauer effect studies of plasma deposited Fe₇C₃, thin films. Thin film coatings of iron carbide deposited on glass microscope cover slips were made by introducing Fe(CO)₅, with H₂ carrier gas into a plasma reactor. X-ray diffraction showed the resulting films to be Fe₇C₃. Hysteresis loops and magnetization curves, obtained by using a SQUID magnetometer, gave film coercivities ranging from 280Oe at 300K to 1130Oe at 10K. In contrast, the coercivity of bulk Fe₇C₃ is about 35 Oe.