Magnetic Properties of Fe@FeSiAl Oxide Nanoparticles and Magneto-Dielectric Properties of Their Composite Sheets

Macroscopically core-shell structured Fe@FeSiAl oxide nanoparticles and their composite sheets were manufactured through a series of simple procedures such as solution combustion synthesis, hydrogen reduction, mixing of polymer and filler, and hot pressing of stacked tape cast films. To evaluate the high frequency magnetic properties of the Fe composite nanopowders, metallic element composition (Fe:Si:Al), hydrogen reduction temperature were controlled and then analyzed using Landau-Lipschitz-Gilbert equation and extended EMT mixing rule. The magneto-dielectric properties of the composite sheet containing 75 wt% 95:3:2 in Fe:Si:Al content powder were a permittivity of 2.5 with a dielectric loss of <;1% and a permeability of 2.0 with a magnetic loss of <;15% at 1 GHz. This result showed that the bandwidth of a patch antenna with the composite sheet substrate could be improved by 4.9 times wider compared with that of a patch antenna with Co2Y type hexagonal Ba ferrite substrate. Furthermore, the composite sheet has a good mechanical flexibility, which leads to a conformal structure. Thus, the composite sheet can be a good candidate for antenna substrate of mobile handsets.