Properties of Fe/SiO_2 Core-shell Composite Particles with Different Nanoshell Thickness

Using a sol-gel route with polyvinyl pyrrolidone as the surfactant,the carbonyl iron microparticles were uniformly and fleetly coated by SiO_2 nanoshell,whose thickness was conve- niently different by changing reaction time.The influences of shell thickness on the properties of the Fe/SiO_2 core-shell particles were studied.The results show that increasing the thickness of SiO_2 nanoshell(D_(shell)),the anti-oxidation property of the Fe/SiO_2 core-shell composite parti- cles is obviously improved while microwave permittivity decreased monotoneously.The saturation magnetization shows a maximum value while both the coercivity and remnant magnetization show minimum values at D_(shell)=15nm.Meanwhile,the radar absorbing coating based on the Fe/SiO_2 core-shell composite particles with D_(shell)=15nm shows a maximum bandwidth of more than 10GHz, in which the reflective loss is less than-8dB.