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Nobuyuki Hiratsuka - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic properties of La–Co substituted Barium Ferrite thin films with large magnetic anisotropy
    Journal of Magnetism and Magnetic Materials, 2004
    Co-Authors: Koichi Kakizaki, H. Taguchi, Nobuyuki Hiratsuka
    Abstract:

    Abstract Barium Ferrite thin films with lanthanum ions and cobalt ions substituted for Barium ions and iron ions have been prepared by conventional diode sputtering method. The hexagonal magnetoplumbite structure was formed by an annealing at 800°C or above. La–Co-substituted Barium Ferrite thin films had large magnetic anisotropy compared with non-substituted Barium Ferrite thin films. Moreover, an attempt was also made to reduce the film thickness of La–Co-substituted Barium Ferrite thin films, in order to utilize them as perpendicular magnetic recording media.

  • The effect of AlN underlayer on c-axis orientation of Barium Ferrite thin films for perpendicular magnetic recording media
    Journal of Magnetism and Magnetic Materials, 2001
    Co-Authors: Koichi Kakizaki, Hideaki Watanabe, Nobuyuki Hiratsuka
    Abstract:

    Abstract The effect of AlN underlayer on c-axis orientation of Barium Ferrite thin films and their magnetic properties have been investigated. On the AlN underlayer with a thickness of 30 nm, Barium Ferrite film with a thickness of 50 nm was deposited at room temperature. As the deposited Barium Ferrite film was not crystallized, it was post-annealed at 800°C for 5 h in air. The c-axis of crystallized Barium Ferrite was oriented perpendicular to the film surface that was caused by the effect of the AlN underlayer.

  • Recording Characteristics of Acicular Barium Ferrite Particulate Medium with Perpendicular Magnetic Anisotropy
    Journal of the Japan Society of Powder and Powder Metallurgy, 1993
    Co-Authors: Koichi Kakizaki, Hiroyuki Sano, Minoru Fujita, Nobuyuki Hiratsuka
    Abstract:

    Acicular Barium Ferrite particles in which the doping Co2+ ions and Ti4+ ions were substituted for Fe3+ ions have been prepared by the sintering method. The acicular BaCo0.7Ti0.7Fe10.6O19 particles which had coercivity of about 1 kOe were mixed with a binder, then the resulting mixture was coated on a PET film under a magnetic field of 8 kOe applied vertically to the surface of the film. The recording characteristics of the acicular Barium Ferrite magnetic tapes were measured by using commercially available open reel tape deck.The output waveform of the acicular Barium Ferrite magnetic tapes showed that the tapes had the perpendicular magnetic anisotropy. However, the low packing density of the particles and the rough surface resulted in the low value of the signal output in the high frequency. Therefore, we attempted to improve the dispersion quality and the spacing loss. The signal output of the improved acicular Barium Ferrite magnetic tape was about 2 times as large as that of the previously prepared tape.

M.h. Kryder - One of the best experts on this subject based on the ideXlab platform.

  • C-Axis Perpendicularly Oriented Barium Ferrite Thin Film Media on Silicon Substrate
    MRS Proceedings, 1999
    Co-Authors: Zailong Zhuang, M.h. Kryder, Robert M. White, David E. Laughlin
    Abstract:

    ABSTRACTBarium Ferrite thin films with excellent perpendicular c-axis orientation were successfully fabricated on Si substrate without any buffer layer. To compensate for possible Barium deficiency due to the inter-diffusion between films and substrate, a Barium-rich target was used. For a 900 Å-thick film, the perpendicular remanent squareness is about 0.9, while the in-plane remanent squareness is about 0.3. The saturation magnetization (Ms) is about 220 emu/cc, while the coercivity is around 3500 Oe. X-ray diffraction (XRD) results show the (001) perpendicular c-axis texture in the films. It was also found that the rapid thermal annealing conditions greatly affect the magnetic properties of Barium Ferrite films. With a certain flow rate of oxygen gas in the rapid thermal annealer (RTA), Barium Ferrite films generally crystallize with good perpendicular c-axis texture. Without oxygen gas, the hexagonal Barium Ferrite phase fails to develop; instead spinel Fe3O4 phase forms. The reason for the collapsing of hexagonal Barium Ferrite texture is thought to be an oxygen deficiency in the Barium Ferrite films due to the reduction of oxygen in the films during the high temperature annealing.

  • Barium Ferrite thin films without a dead layer
    IEEE Transactions on Magnetics, 1998
    Co-Authors: Yingjian Chen, Maithri Rao, David E. Laughlin, M.h. Kryder
    Abstract:

    A Barium Ferrite layer with low-Ba content was used as an underlayer for a high-Ba content Barium Ferrite thin film. During the post-deposition annealing, the underlayer which has a lower nucleation rate than the top layer prevented grains from nucleating in the interdiffused region at the interface with the substrate. As a result, the magnetic properties were dramatically improved as indicated by much higher coercivity squareness S* and narrower switching field distribution.

  • Tribological properties of Barium Ferrite films
    IEEE Transactions on Magnetics, 1995
    Co-Authors: M. Scherge, C.l. Bauer, M.h. Kryder
    Abstract:

    Acoustic emission and friction coefficients have been measured during start-stop and continuous sliding for pure and doped Barium Ferrite films, without lubrication, and compared with concomitant surface topography and magnetic properties. Barium Ferrite films averaging about 100 nm in thickness, were produced on thermally oxidized Si substrates by sputter deposition and then furnace or rapid thermal annealed in order to develop optimum microstructure and magnetic characteristics. Four varieties of (hexagonal) Barium Ferrite were produced and investigated: pure Barium Ferrite with longitudinal and perpendicular c-axis orientation, pure Barium Ferrite with perpendicular orientation with Pt underlayer and doped Barium Ferrite. Results are compared with data obtained from commercial disks with a carbon overcoat.

  • Microstructural investigations of Barium Ferrite longitudinal thin‐film media
    Journal of Applied Physics, 1994
    Co-Authors: B.y. Wong, David E. Laughlin, Xiaoyu Sui, M.h. Kryder
    Abstract:

    Crystalline Barium Ferrite films with in‐plane magnetic anisotropy have been obtained by postdeposition annealing of amorphous sputtered films. The magnetic properties, the crystallographic texture, and the microstructure are very sensitive to the sputtering and postdeposition annealing conditions. It was found that both Hc and the grain size decrease with the addition of Co and Ti ions. However, an excessive amount of dopants leads to a loss in the in‐plane anisotropy. Barium Ferrite films produced by this technique contain physical voids or channels separating the grains which help to decrease the exchange coupling between grains.

  • Effects of CoTi-doping on longitudinal Barium Ferrite thin film media
    IEEE Transactions on Magnetics, 1994
    Co-Authors: Xiaoyu Sui, M.h. Kryder
    Abstract:

    It is shown that the coercivity of Barium Ferrite thin film media can be adjusted over a very wide range from 1000 Oe to 4000 Oe by the proper amount of CoTi-doping. The coercivity decreases dramatically with increasing CoTi concentrations in the film, while the saturation magnetization decreases only slightly. The optimized S/sub q/, S* and SFD values are relatively unaffected by CoTi-doping. The grain size decreases as the amount of CoTi-doping increases. A multilayer structure consisting of alternating pure Barium Ferrite and CoTi-doped Barium Ferrite layers has been demonstrated to be useful for controlling the overall film composition through a diffusion process. The direct correspondence between the coercivity and the composition provides a guideline for the practical use of this material. >

Koichi Kakizaki - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic properties of La–Co substituted Barium Ferrite thin films with large magnetic anisotropy
    Journal of Magnetism and Magnetic Materials, 2004
    Co-Authors: Koichi Kakizaki, H. Taguchi, Nobuyuki Hiratsuka
    Abstract:

    Abstract Barium Ferrite thin films with lanthanum ions and cobalt ions substituted for Barium ions and iron ions have been prepared by conventional diode sputtering method. The hexagonal magnetoplumbite structure was formed by an annealing at 800°C or above. La–Co-substituted Barium Ferrite thin films had large magnetic anisotropy compared with non-substituted Barium Ferrite thin films. Moreover, an attempt was also made to reduce the film thickness of La–Co-substituted Barium Ferrite thin films, in order to utilize them as perpendicular magnetic recording media.

  • The effect of AlN underlayer on c-axis orientation of Barium Ferrite thin films for perpendicular magnetic recording media
    Journal of Magnetism and Magnetic Materials, 2001
    Co-Authors: Koichi Kakizaki, Hideaki Watanabe, Nobuyuki Hiratsuka
    Abstract:

    Abstract The effect of AlN underlayer on c-axis orientation of Barium Ferrite thin films and their magnetic properties have been investigated. On the AlN underlayer with a thickness of 30 nm, Barium Ferrite film with a thickness of 50 nm was deposited at room temperature. As the deposited Barium Ferrite film was not crystallized, it was post-annealed at 800°C for 5 h in air. The c-axis of crystallized Barium Ferrite was oriented perpendicular to the film surface that was caused by the effect of the AlN underlayer.

  • Recording Characteristics of Acicular Barium Ferrite Particulate Medium with Perpendicular Magnetic Anisotropy
    Journal of the Japan Society of Powder and Powder Metallurgy, 1993
    Co-Authors: Koichi Kakizaki, Hiroyuki Sano, Minoru Fujita, Nobuyuki Hiratsuka
    Abstract:

    Acicular Barium Ferrite particles in which the doping Co2+ ions and Ti4+ ions were substituted for Fe3+ ions have been prepared by the sintering method. The acicular BaCo0.7Ti0.7Fe10.6O19 particles which had coercivity of about 1 kOe were mixed with a binder, then the resulting mixture was coated on a PET film under a magnetic field of 8 kOe applied vertically to the surface of the film. The recording characteristics of the acicular Barium Ferrite magnetic tapes were measured by using commercially available open reel tape deck.The output waveform of the acicular Barium Ferrite magnetic tapes showed that the tapes had the perpendicular magnetic anisotropy. However, the low packing density of the particles and the rough surface resulted in the low value of the signal output in the high frequency. Therefore, we attempted to improve the dispersion quality and the spacing loss. The signal output of the improved acicular Barium Ferrite magnetic tape was about 2 times as large as that of the previously prepared tape.

Wang Yan - One of the best experts on this subject based on the ideXlab platform.

  • Preparation and electromagnetic wave absorption properties of M-type Barium Ferrite
    Materials Science and Technology, 2010
    Co-Authors: Wang Yan
    Abstract:

    Hexagonal Barium Ferrite powders were prepared by sol-gel auto-combustion method in order to research the microwave absorption properties of M-type Ferrite. The crystal structure,decompounding process, micrograph and microwave absorption properties of the sample were studied by means of XRD,TG-DTA, SEM and vector network analyzer. According to the transmission line theory,the reflection loss of electromagnetic radiation was calculated and the optimum thickness was predicted. The study shows that the prepared sample is found to be M-type Barium Ferrite with single phase. The optimum thickness is 0. 35 cm,the minimum reflection loss reaches-13. 5 dB,and the bandwidth is 0. 7 GHz when the reflection loss is less than-10 dB. It means that M-type Barium Ferrite has good microwave absorption capability.

Wang Qi-jie - One of the best experts on this subject based on the ideXlab platform.

  • Barium Ferrite Are Prepared for Using Citric Acid Sol-Gel Technique
    Bulletin of the Chinese ceramic society, 2006
    Co-Authors: Wang Qi-jie
    Abstract:

    Barium Ferrite nanoparticles were prepared by using sol-gel technique. Influence of three methods of preparation process on formation process of Barium Ferrite was studied. The result shows that there were several factors of sol-gel preparation: temperature, pH, citric acid molar ratio, auxiliary reagent, the disposal of impurity, and the choose of sol circumfluence.The magnetic characteristics of Barium Ferrite was determined by its particle size, shape, particle distributing,and the degree of reuniting. Pure particles of Barium Ferrite which was called BaM magnetic materials was obtained by three methods, The method Ⅲ is the best. Pure particles of Barium Ferrite with an average size of 155nm,a coercive force of 407.9kA/m, and a specific satu-ration magnetization of 58.78Am~2/kg can be obtained at 900℃.