The Structure of Electroless Cobalt Films as Revealed by Electron Microscopy

A brief survey, using transmission electron microscopy, of the crystallite structure of magnetic electroless cobalt films deposited from an alkaline hypophosphite bath on to glass substrates has been undertaken. With increasing pH values from 7.4 to 8.5, the overall continuity of the films improved for a given thickness, although the crystallites themselves became individually isolated. This isolation is responsible for the increase in coercivity observed over the same pH range. Micrographs of various specimens are included to illustrate the features discussed.