Synthesis, microstructure and magnetic properties of Fe3Si0.7Al0.3@SiO2 core-shell particles and Fe3Si/Al2O3 soft magnetic composite core

Fe3Si0.7Al0.3@SiO2 core shell particles and Fe3Si/Al2O3 soft magnetic composite core have been synthesized via a modified stober method combined with following high temperature sintering process. Most of conductive Fe3Si0.7Al0.3 particles could be uniformly coated by insulating SiO2 using the modified stober method. The Fe3Si0.7Al0.3@SiO2 core shell particles exhibited good soft magnetic properties with low coercivity and high saturation magnetization. The reaction 4A1+3SiO(2)=2 alpha-Al2O3+3Si took place during the sintering process. As a result the new Fe3Si/Al2O3 composite was formed. The Fe3Si/Al2O3 composite core displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher electrical resistivity and lower core loss than the pure Fe3Si0.7Al0.3 core. The method of introducing insulating layers surrounding magnetic particles provides a promising route to develop new and high compact soft magnetic materials with good magnetic and electric properties. (C) 2015 Elsevier Inc. All rights reserved.