Title :
Magnetic cores usable in gigahertz range: permalloy/Ni-Zn ferrite microcomposite made by low-temperature wet process
Author :
Kim, Duksil ; Ohnishi, Masanori ; Matsushita, Nobuhiro ; Abe, Masanori
Author_Institution :
Tokyo Inst. of Technol., Japan
Abstract :
Permalloy (Ni47Fe53) microspheres of 4 and 8 μm in average diameter were encapsulated with Ni-Zn ferrite by ultrasound enhanced ferrite plating from an aqueous solution at 80°C at pH=6-9. The ferrite-encapsulated microspheres were compacted to toroidal cores, on which complex permeability (μ=μ´-jμ´´) was measured. The natural ferromagnetic resonance frequency fr (criterion for usable frequency), and μ´ of the cores exceeded Snoek´s limit for Ni-Zn ferrite bulk by one order of magnitude. The cores exhibited one-turn-coil impedance exceeding 40 Ω at 1-3 GHz, suggesting that they will be applied to gigahertz electromagnetic compatibility bead inductors to suppress electromagnetic noises. In addition, the cores will be applied to low-loss inductors operated at tens of megahertz, since they have Q=μ´/μ´´>100 up to 45 MHz when the microspheres were plated at pH=6.
Keywords :
Permalloy; electromagnetic compatibility; ferrites; ferromagnetic materials; ferromagnetic resonance; liquid phase deposited coatings; magnetic cores; magnetic permeability; magnetic thin films; nanocomposites; nickel compounds; zinc compounds; 1 to 3 GHz; 4 to 8 micron; 40 ohm; 45 MHz; 80 degC; Ni47Fe53 microspheres; Ni47Fe53-NiZnFe2O4; Snoek´s limit; aqueous solution; complex permeability; gigahertz electromagnetic compatibility bead inductors; gigahertz range; low-loss inductors; low-temperature wet process; magnetic cores; natural ferromagnetic resonance frequency; one-turn-coil impedance; permalloy/Ni-Zn ferrite microcomposite; suppress electromagnetic noises; toroidal cores; ultrasound enhanced ferrite plating; Electromagnetic compatibility; Ferrites; Inductors; Iron; Magnetic cores; Magnetic resonance; Permeability measurement; Resonant frequency; Ultrasonic imaging; Ultrasonic variables measurement;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2003.816050