The effect of rare-earth oxide CeO2 on the electromagnetic properties of ferrite-ceramic composite materials
In this work, we present the influence of rare-earth element additions on this new composite material. A great improvement of the electromagnetic properties was obtained. The constituent chemicals were mixed in the stoichiometric composition, calcined at 850degC for 2 h and blended with PVA to press into steroidal or disc shaped specimens. These specimens were sintered at 900degC for 2.5 h in air. The complex permeability, capacity and impedance were measured with HP4291B and 4291A instruments, respectively, in the frequency range from 1MHz to 2GHz.
Electromagnetic properties of a new ferrite-ceramic low-temperature cocalcined (LTCC) composite materials
A new ferrite-ceramic composite material with inductive, capacitive, and impedance properties was fabricated by a solid-state reaction. The composite materials were prepared with ferromagnetic NiCuZn ferrites and ferroelectric BaTiO/sub 3/ perovskite. Co/sup 2+/, Bi/sup 3+/, Y/sup 3+/, Dy/sup 3+/, and Ca/sup 2+/ ions are selected to improve the electromagnetic properties. We found that this new material has excellent frequency dependence of magnetic and dielectric properties, which can be used not only as inductor and resistor materials but also as capacitor materials in the wide range of 1 KHz to 4 GHz. At 1 MHz, the dielectric constant /spl epsiv/' of the composite material is 60-120, and the initial permeability /spl mu/' is 5.6-13.
Micromechanics approach for effective magnetostriction of composite materials
A micromechanics method is developed for the effective magnetostrictive behavior of magnetostrictive composite materials. Explicit relations for determining the effective magnetostriction of the particulate composites with cubic magnetostrictive crystallites are derived and reduce to the well-known results in the case of simple polycrystals with elastically isotropic magnetostrictive crystallites. Numerical calculations for the effective saturation magnetostriction of SmFe2/Fe or Al, and Terfenol-D/epoxy composites show that the theoretical estimates correlate well with experimental data, and they also show the interesting magnetostrictive behavior of the composites.