The improvement of microwave properties for Co flakes after silica coating

▶ Sub-micrometer cobalt flakes were fabricated by hydrazine reduction in aqueous solution and coated with silica layers. ▶ Cut off frequency is about 4 GHz for all coated samples, the performance of the real part of permeability μ′ was greatly improved when f was lower than 4 GHz. ▶ Eddy current loss is suppressed after silica coating.