Microwave and millimeter wave dielectric permittivity and magnetic permeability of epsilon-gallium-iron-oxide nano-powders
- Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States)
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
In millimeter wave frequency range, hexagonal ferrites with high uniaxial anisotropic magnetic fields are used as absorbers. These ferrites include M-type barium ferrite (BaFe{sub 12}O{sub 19}) and strontium ferrite (SrFe{sub 12}O{sub 19}), which have natural ferromagnetic resonant frequency range from 40 GHz to 60 GHz. However, the higher frequency range lacks suitable materials that support the higher frequency ferromagnetic resonance. A series of gallium-substituted ε-iron oxides (ε-Ga{sub x}Fe{sub 2−x}O{sub 3}) are synthesized, which have ferromagnetic resonant frequencies appearing over the frequency range of 30 GHz to 150 GHz. The ε-Ga{sub x}Fe{sub 2−x}O{sub 3} is synthesized by the sol-gel method. The particle sizes are observed to be smaller than 100 nm. In this paper, in-waveguide transmission and reflection method and the free space magneto-optical approach have been employed to study these newly developed ε-Ga{sub x}Fe{sub 2−x}O{sub 3} particles in millimeter waves. These techniques enable to obtain precise transmission spectra to determine the dielectric and magnetic properties of both isotropic and anisotropic ferrites in the microwave and millimeter wave frequency range from single set of direct measurements. The complex dielectric permittivity and magnetic permeability spectra of ε-Ga{sub x}Fe{sub 2−x}O{sub 3} are shown in this paper. Strong ferromagnetic resonances at different frequencies determined by the x parameter are found.
- OSTI ID:
- 22409956
- Journal Information:
- Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
BARIUM COMPOUNDS
DIELECTRIC MATERIALS
FERRITES
FERROMAGNETIC RESONANCE
FREQUENCY DEPENDENCE
GALLIUM COMPOUNDS
GHZ RANGE
IRON OXIDES
MAGNETIC FIELDS
MAGNETIC SUSCEPTIBILITY
MICROWAVE RADIATION
PARTICLE SIZE
PERMITTIVITY
POWDERS
SOL-GEL PROCESS
STRONTIUM COMPOUNDS