Adsorption of Metals on Iron Particles in Mercury

Abstract

Spherical iron particles in mercury were prepared by electrodeposition, and then aged to give particles with an average diameter of 180 Å. The addition of Pb, Cd, Ag, Cr, Ba, Cu, Bi, and In to the iron particles in mercury had no effect on the magnetic properties but As, Mn, Zn, Sn, Sb, Al, Ti, Mo, and Ni increased the coercive force. It was concluded that only those metals which could form intermetallic compounds with iron would increase the coercive force of iron particles in mercury. Quantitative measurements on Mn, Zn, Sn, and Sb showed that the coercive force increased, in the order given, without changing the magnetic moment. Thus, no compound formation actually occurred. The amount of these metals required to produce the complete magnetic effect corresponded to the adsorption of approximately a monolayer on the iron particle surfaces. The magnitude of the increase in coercive force was proportional to the atomic diameter of the adsorbed species as expected from the assumption that the increase in coercive force is due to the decrease in magnetostatic interaction caused by the absorption of metal atoms on the iron particle surfaces.