A simple process for ferrite film preparation from one solution without using hazardous oxidizing agent

A process for ferrite film preparation using an aqueous solution was developed and named as “one solution spray technique” (OSST). Highly crystallized spinel ferrite films can be prepared by spraying only one solution at a very low temperature of 90°C without any postannealing. In contrast to the conventional spray technique (CST), two solutions (reaction solution and an oxidizing solution containing pH buffer) were independently sprayed. In OSST, reaction solution containing a mixture of FeCl2, CH3COOK, and urea was used. The Fe3O4 films prepared by OSST exhibited a real permeability of μ′=35 and a very high resonance frequency of fr=1.25GHz, which was superior to that for films prepared by CST (fr=850MHz). The μ″×f spectra, which are proportional to the noise suppression effect of the films, proved that the films prepared by this technique have suitable properties to be used as conducted noise suppressors in the gigahertz range.