He Huahui

Effects of Fe2+ content in raw materials on Mn-Zn ferrite magnetic properties

Abstract The magnetic properties of Mn–Zn ferrite such as initial permeability, saturation magnetization, Curie temperature, resistivity and power loss are affected greatly by the Fe 2+ content in the raw materials. The experimental results show that low resistivity ( ρ ) and high eddy current loss ( P e ) are induced by the superfluous Fe 2+ content in the raw materials; the scant Fe 2+ content in the raw materials will increase hysteresis loss ( P h ) and decrease Curie temperature ( T c ), saturation magnetization ( M s ) and initial permeability ( μ i ).

Wide-band electromagnetic wave absorber of rubber-ferrite

Two different compositions with Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 2.1/Fe/sub 9.9/ O/sub 19/ and Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 3.2/Fe/sub 8.8/O/sub 19/ of barium ferrite with a magnetoplumbite structure (M-type) had been obtained by conventional ceramic technology. The complex permeability and permittivity of the materials were measured in the 2-18 GHz band. Ba M-type ferrite materials mixed with polyvinyl chloride, plasticizer and frit are pressed to form flakes (180 mm/spl times/180 mm/spl times/2 mm) of rubber-ferrite. The absorption properties of the single layer rubber-ferrite absorber are measured by an Agilent 8722ES network analyzer (2-18 GHz). Compared with the theoretical calculation, it was found that preferable properties of microwave absorption were obtained by using a bank of two ferrite materials singly over a narrow frequency region. Almost all of the samples in the multi-layer rubber-ferrite absorber exhibited a minimum reflection loss less than -10 dB with a thickness (d/sub m/) 22 mm.

Optical mode conversion in a ferrimagnetic film containing magnetostatic forward volume wave

This paper presents a general description of the mode coupling in the optical waveguide containing a magnetostatic forward volume wave(MSFVW). The power-conversion efficiency of TEI-TMm modes have been obtained for several kinds of 1/m, which are corresponding to the different center frequency. The multi-band modulator has been predicted and the advantage of modulation by MSFVW over MSSW has been discussed.

Magneto-optical properties of Ce ion-implanted YIG film

Abstract Ce ions were implanted into YIG film with doses of 10 14 ∼ 10 16 ions/cm 2 at an energy of 500 keV. The X-ray diffraction spectrum, optical absorption spectrum, and Faraday rotation were measured for as-grown, as-implanted and annealed samples. Because of the damage induced by ion-implantation, the as-implanted film showed additional optical absorption and decreased FR. By annealing the as-implanted sample at high temperature, the lattice geometry was restored, which reduced the optical absorption and increased the FR.

Magnetostatic mode spectra of a double layered film having different magnetization and anisotropy energies

Abstract The Damon and Eshbch theory for the magnetostatic modes in a single crystal film has been extended to a double layer system having different magnetizations as well as different uniaxial anisotropy energies. The dispersion equation is derived and applied to the magnetostatic spectra obtained from a La, Ga: YIG-La: YIG double layer film. The observed spectra are in good agreement with those calculated from the extended DE-theory.

Measure the Thickness of the Thin-Film Single-Slice-Capacitor

According to wave-absorbing materials electricity characteristic, this text created a kind of new high-performance, low-cost capacitance type absorbing-wave coats thickness measuring system. Carry out a research of thin film measurement which from nm-level to micron-level. According to the theory which capacitor working in electric field, it design a special single-piece capacitance sensor. This system can carry on a measurement to the thickness of thin film from nm-level to micron-level. Pass to adopt a kind of new capacitance signal to collect the framework type integration chip(Frame ASIC) CAV424 and shield measure and low price position RISC microcontroller, it carry out a method combine with the difference technique and three-signals-inspect technique. The system can automatically adjust null, correct and remove a great deal of errors. Because the microcontroller have inside place 10 position A/D conversion and driver of LCD, the CAV424 outputs differential voltage signal can directly with the ADC connection, link in the microcontroller, and the structure of system is very simple.According to wave-absorbing materialpsilas electricity characteristic, this text created a kind of new high-performance, low-cost capacitance type absorbing-wave coatpsilas thickness measuring system. Carry out a research of thin film measurement which from nm-level to micron-level. According to the theory which capacitor working in electric field, it design a special single-piece capacitance sensor. This system can carry on a measurement to the thickness of thin film from nm-level to micron-level. Pass to adopt a kind of new capacitance signal to collect the framework type integration chip(Frame ASIC) CAV424 and shield measure and low price position RISC microcontroller, it carries out a method combine with the difference technique and three-signals-inspect technique. The system can automatically adjust null, correct and remove a great deal of errors. Because the microcontroller has inside place 10 position A/D conversion and driver of LCD, the CAV424 outputpsilas differential voltage signal can be directly with the ADC connection, link in the microcontroller, and the structure of system is very simple.

The theory of electromagnetic wave propagation in a ferromagnetic film

A general analysis of the retarded modes in a metal-backed ferromagnetic film is presented. The dispersion curves have been solved numerically. A comparison with the magnetostatic approximation has been made, which shows when the approximation is effective.

A study of dispersion characteristics of magnetostatic surface wave (MSSW) delay lines in the multiple layer films

Abstract A correct dispersion equation for MSSW propagating in multiple layer films has been derived. The delay-frequency curves with the various parameters of the film and the applied field have been given. This paper first reports some experimental results of the LPE grown multiple layer films (GGG-La; YIG-GGG-La : YIG) and the MSSW delay lines consisting of the multiple LPE films with one side metallized. The device characteristics of a linear delay over 400 MHz bandwidth in the 3.6 to 4.4 GHz frequency range have been exhibited to be in agreement with theory.

Oxidizing treatments on bismuth-substituted magnetic garnet films: an X-ray photoelectron study

X-ray photoelectron spectroscopy (XPS) studies on bismuth-substituted iron garnet films have been conducted. Quantitative analyses of iron ions in the magneto-optical film with XPS are presented for the first time, and the effects of oxidations on the optical absorptions are revealed. A new view that the optical absorption is closely related to the energy splitting of the characteristic XPS lines of iron ions in the magneto-optical film is suggested.

Theory of magnetic excitions in layered media

A general way of calculating and analyzing the characteristics of magnetic excitation on layered media is presented. The magnetostatic wave spectrum in layered media and the amplitude distribution of the potential are given.