• Title, Summary, Keyword: ferrite substrate

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Effects of the Substrate Temperature on the Properties of Ni-Zn-Cu Ferrite Thin Films Deposited by RF Magnetron Sputtering (RF Magnetron Sputtering에 의해 증착된 Ni-Zn-Cu Ferrite 박막의 물성에 미치는 기판온도의 영향)

  • 공선식;조해석;김형준;김경용
    • Journal of the Korean Ceramic Society
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    • v.29 no.5
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    • pp.383-390
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    • 1992
  • We investigated the effect of substrate on the properties of the Ni-Zn-Cu ferrite thin films deposited on SiO2 (1000∼3000${\AA}$) / Si (100) substrate at various conditions by rf magnetron sputtering. A disktype Ni-Zn-Cu ferrite sintered by conventional ceramic process and argon gas were used as a target and a sputtering gas, repectively. The compositions of the thin films measured by EPMA were similar to target composition (Fe: 65.8 at%, Ni: 12.7 at%, Cu: 6.7 at%, Zn: 14.8 at%) irrespective of substrate temperature. Amorphous thin films were deposited when substrate was not intentionally heated, but the films came to crystallize with increasing substrate temperature, and crystalline thin films were deposited at substrate temperature above 200$^{\circ}C$. Below 250$^{\circ}C$ saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) of the ferrite thin film increased with the substrate temperature due to the increase of grain size and the improvement of crystallinity. And above 250$^{\circ}C$, Ms, Mr increased slightly, but Hc of the amorphous thin films increased due to crystallization, whereas that of the crystalline thin films decreased because of grain growth and stress release.

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Nanoparticulate Co-Ferrite Thin Films on Glass Substrate Prepared by Sol-Gel Method (유리기판에 sol-gel법으로 제조된 나노입자 Co-ferrite 박막의 특성)

  • 오영제;최현석;최세영
    • Journal of the Korean Ceramic Society
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    • v.37 no.5
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    • pp.425-431
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    • 2000
  • Cobalt ferrite thin films on Corming glass substrate were fabricated by a sol-gel method. Cobalt ferrite thin films with the grain size of 20-35 nm and thickness of 50nm were obtained. Rapid thermal annealing (RTA) and Annealing processes were adopted for comparison of characteristics of the films. Coercivity values were changed with thermal condition and magnetization values were increased as a function of soaking time. With prolonged soaking time, however, it was decreased because of the diffusion of cations from the glass substrate. The RTA process in preparation of cobalt ferrite thin film was the effective way to prevent and to form a single spinel phase in reduced soaking time. The film heated at 600$^{\circ}C$ for 30 minutes by RTA had coercivity of 2,600 Oe, saturation magnetization 460 emu/㎤, and Mr$.$$\delta$ of 1.43 memu/$\textrm{cm}^2$.

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Fabrication of Barium Ferrite Films by Sol-Gel Dip Coating and Its Properties.

  • T. B. Byeon;W. D. Cho;Kim, T. O.
    • Journal of Magnetics
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    • v.2 no.1
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    • pp.16-21
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    • 1997
  • Those were investigated, the crystallographic, morphological, and magnetic properties of barium ferrite film (SiO2/Si substrate) prepared by sol-gel dip coating. Appropriate sol was prepared by dissolvin barium and iron nitrate in ethylene glycol at 80$^{\circ}C$. To obtain the films, thermally oxidized p-type silicon substrate with (111) of crystallographic orientation were dipped into the sol, dried at 250$^{\circ}C$ to remove organic material, and heated at 800$^{\circ}C$ for 3 hours in air for the crystallization of barium ferrite. It was found that the particles of barium ferrite formed on the substrate exhibited needle-like shape placing parallel to the substrate and its c-axis is long axis direction. There was tendency that the coercive force in horizontal direction to the substrate was higher than that in vertical direction to it. This tendency was profound in large thickness.

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The Preparation and Magnetic Properties in Ba-ferrite Film on the A12O3 Substrate (A12O3을 하지층으로 하는 Ba-ferrite 박막의 제조 및 자기적 특성에 관한 연구)

  • Sur, Jung-Chul;Park, Chul-Jin;Choi, Jung-Wan
    • Journal of the Korean Magnetics Society
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    • v.15 no.2
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    • pp.125-129
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    • 2005
  • Ba-Ferrite thin films were prepared on $A1_2O_3$ substrate by a pulsed laser deposition system and characterized by SEM, $M\ddot{o}$ssbauer spectroscopy and VSM. The appropriate conditions of pulsation in Ba-ferrite was the oxygen pressure of 0.1 Torr at a substrate temperature of $400^{\circ}C$ and the thickness was variable with the deposition time. Ba-ferrite crystals had the forms of hexagonal plate in the 5 minute deposited film and the needle grains coexisted with the increasing film thickness. $M\ddot{o}ssbauer$ spectroscopy assured that the direction of atomic spin in Fe ion tends to normal to the substrate in the hexagonal plate. The VSM curves have the two types hysteresis of hexagonal and needle phase.

Two-Layered Microwave Absorber of Ferrite and Carbon Fiber Composite Substrate

  • Han-Shin Cho;Sung-Soo Kim
    • Journal of Magnetics
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    • v.3 no.2
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    • pp.64-67
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    • 1998
  • Microwave absorbing properties of ferrite-epoxy composite (absorbing layer) attached on the carbon fiber polymer composite (reflective substrate) are analyzed on the basis of wave propagation theory. A modified equation for wave-impedance-matching at the front surface of absorbing layer including the effect of electrical properties of the quasi-conducting substrate is proposed. Based on this analysis, the frequency and layer dimension that produce zero-reflection can be estimated from the intrinsic material properties of the obsorbing layer and the substrate. It is demonstrated that the microwave reflectivity of carbon fiber composite has a strong influence on the microwave absorbance of front magnetic layer.

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The Preparation and Magnetic Properties in Ba-ferrite Film (Ba-ferrite 박막의 제조 및 자기적 특성에 관한 연구)

  • Sur, Jung-Chul;Kim, Dae-Sung;Ha, Tae-Yang;Lee, Jae-Gwang
    • Journal of the Korean Magnetics Society
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    • v.13 no.2
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    • pp.64-69
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    • 2003
  • Ba-ferrite thin films were prepared on Si substrate with ${\alpha}$-Fe$_2$O$_3$ underlayer by a pulsed laser deposition system and characterized by X-ray, SEM, Mossbauer spectroscopy and VSM. The appropriate conditions of pulsation in ${\alpha}$-Fe$_2$O$_3$ and Ba-ferrite were the oxygen pressure of 0.1 Torr at a substrate temperature of 400$^{\circ}C$. Ba-ferrite crystals had the forms of ellipsoidal or needle and the grains shaped the more lumps with increasing the film thickness. Mossbauer spectroscopy assured that the direction of atomic spin in Fe ion was not random but had the tendency of arrangement normal to the substrate. The coercive force and squareness of hysteresis were larger in normal than in plane to the substrate but, the magnetic saturation moment was contrary to them. The spin arrangement was strongly affected by ${\alpha}$-Fe$_2$O$_3$ underlayer and the high coercive force and squareness were influenced by this. The crystal structure was conformed to be a Magntoplumbite symmetry with the hexagonal unit cell and the lattice constant of a increased with increasing film thickness, while c decreased

Ferrite-based wideband circularly polarized microstrip antenna design

  • Mashhadi, Mostafa;Komjani, Nader;Rejaei, Behzad;Ghalibafan, Javad
    • ETRI Journal
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    • v.41 no.3
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    • pp.289-297
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    • 2019
  • In this paper, a wideband, circularly polarized patch antenna is proposed that leverages the unidirectional resonant modes of a circular patch mounted on top of a grounded dielectric-ferrite substrate. The proposed antenna is fed via the proximity coupling method and several parasitically coupled patches are placed on a dielectric superstrate to enhance the impedance bandwidth of the antenna. The resonant modes of the structure rotate only in the clockwise or counter clockwise directions. In the frequency range where the effective permeability of the ferrite layer is negative, the resonance frequencies of these modes differ significantly, which produces a large axial ratio (AR) bandwidth. For the proposed antenna, the numerical results show the 10 dB impedance bandwidth to be around 44% and the 3 dB axial ratio bandwidth to be higher than 64%.

Analysis of multiple coupled microstrip lines on a magnetized ferrite substrate (자화된 페라이트 기판상의 다중 결합 마이크로스트립 선로 해석)

  • 문영찬;윤상원;창익수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.5
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    • pp.65-74
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    • 1996
  • in this paper, the propagation characteristics of the dominant modes in multiple coupled microstrip lines on a magnetized ferrite substrate are analyzed. The propagation constants and characteristic impedances are calculated by using the spectral domain method. With the numerical results, multi-port impedance parameters as well as scattering parameters are derived from nonreciprocal transmission line equations which are consistent with conventional transmission line theory. In additon, the numerical resutls of nonreciprocal characteristics for various values of structural, material parameters, and external magnetic fields are also presented.

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The Effects of $TiO_2$ Underlayer on Magnetic Properties of Hexagonal Barium-Ferrite(BaM) Thin Films (Hexagonal Barium-Ferrite(BaM) 박막의 미세구조와 자기적 특성에 미치는 $TiO_2$하지층의 효과)

  • 김동현;남인탁;홍양기
    • Journal of the Korean Magnetics Society
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    • v.11 no.3
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    • pp.129-133
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    • 2001
  • In this paper, we studied structural and magnetic properties of Ba-ferrite thin film deposited on Si(100) substrate with TiO$_2$ underlayer. Ba-ferrite thin films with TiO$_2$ underlayer were deposited by reactive RF/DC magnetron sputtering system at room temperature. TiO$_2$ underlayer was reactive sputtered with $O_2$. After deposition, the thin films were annealed at vatious temperatures to get the crystallized sample. Underlayer was used to prevent interdiffusion from Ba-ferrite thin film to substrate. The growth of Ba-ferrite thin films was influenced by TiO$_2$ underlayer. Easy magnetization direction is in-plane. From these results the Ba-ferrite film with TiO$_2$ underlayer can be used as longitudinal recording media.

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