Fe 3 O 4 + δ films prepared by “one-liquid” spin spray ferrite plating for gigahertz-range noise suppressors

We have developed a simple type of ferrite film preparation technique, which we call “one-liquid” spin spraying method. Only one aqueous solution composed of dextran+FeCl2+CH3COOK+NaNO2 is sprayed onto spinning substrates, while, in our previous method, a reaction solution of FeCl2 (source) and an oxidizing solution of CH3COOK(pHbuffer)+NaNO2(oxidizer) were sprayed simultaneously. Dextran [(C6H12O6)n, n=1100–1700] suppresses iron hydroxides from precipitating in the aqueous solution. On optimized conditions, we deposited Fe3O4+δ films to the thickness of 1.6μm for 30min, obtaining film deposition rate of 52nm∕min. The films exhibited good performance of conducted noise suppression; we obtained loss parameter ΔPloss of 33% at 10GHz of Fe3O4+δ films, which was approximately equal to that obtained for the commercialized noise suppression of composite sheet type, and reflection loss parameter S11, less than −10dB. Thus one-liquid method as well will provide a method to prepare the noise suppressors of Fe3O4+δ films workable in the gigahertz range.