Teruyoshi Hirano

Bi-YIG nanoparticle and plastic hybridized magneto-optical material

We developed a new magnetooptical Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ nanoparticle hybridized material which was composed of Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ nanoparticles and a methylmethacrylate matrix, with and without polymethylmethacrylate. The Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ nanoparticles were prepared using coprecipitation and annealing processes. The hybridized system was prepared by mechanical milling. In this system, polymethylmethacrylate was a very important functional material as a dispersant. Without polymethylmethacrylate, the Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ nanoparticles aggregated. The magnetooptical properties of the solidified clear materials were measured.

Bi-YIG magneto-optical coated films for visual applications

Garnet fine particles of Bi/sub 18/Y/sub 12/Fe/sub 5/O/sub 12/ were prepared by coprecipitation and annealing processes, and were coated on glass or plastic substrates. The annealing was carried out at 650/spl deg/C for 4 h. The obtained particles were identified as garnet by X-ray diffraction. The coated films showed a Faraday rotation of 1 degree in the visible wavelength region. A magnetic field pattern was observed by using a MO film coated on a plastic substrate. The demonstration was made with reflected light. It is expected that Bi-YIG coated films are suitable for a large-size visual MO devices.

Preparation of Bi-YIG particles for display devices

Garnet fine particles are prepared by coprecipitation. The saturation magnetization of the particles increases as the annealing temperature increases. Almost all X-ray diffraction peaks from the particles annealed at 700/spl deg/C for 1 h are assigned to garnet. The prepared particles are classified in order to remove the aggregated large particles which are considered to prevent passing of light. The coercive force lowers to half of the initial value after the classification. Faraday rotation of the particles which are dispersed into methylene iodide is confirmed under a polarization microscope. Faraday rotation of the film coated of the particles are shown as a function of wavelength. >

Novel nanoparticle milling process for Bi-YIG dispersed transparent films

We developed a high-performance milling process with a grooved mill pot. The milling process is able to make highly transparent dispersed materials. Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ nanoparticles were prepared with coprecipitation and annealing processes. The nanoparticle dispersed films were prepared with the milling process and a conventional process. The crystallite sizes of the Bi/sub 1.8/Y/sub 1.2/Fe/sub 5/O/sub 12/ particles in the milled films were 40-50 nm. These sizes were about half that of the films prepared by conventional process. The films containing the particles show high transparency. The light-absorption coefficients of the films were about half that of the films prepared by the conventional process. Magnetooptical properties were also improved. The milling process produces films with a high figure of merit, which is the value of Faraday rotation angle divided by light-absorption coefficient. The milling period was shorter than that of the conventional process.

Nonstoichiometric Properties of Bi-Substituted Yttrium Iron Garnet Sputtered Films

Structural, magnetic and magnetooptical properties of nonstoichiometric Bi-substituted yttrium iron garnet (Bi-YIG) films have been studied in terms of Fe concentration. The garnet films were prepared by rf sputtering using targets which had various Fe contents. In the wide range of Fe content from about 3.9 to 5.4, garnet phases were obtained at an annealing temperature of 650° C. For the Fe contents ranging from 1.9 to 5.1, saturation magnetization increased linearly, and beyond the Fe content of 5.1, it dropped sharply. By considering the magnitude of Faraday rotation of the garnet phase formed in the films (θ F/M s) and Curie temperature, it is expected that the Bi concentration in the garnet-phase crystallites in the prepared films increases as Fe content increases. It was observed, in energy dispersive X-ray spectrometry (EDX) and secondary ion mass spectrometry (SIMS) analyses, that the excess Bi ions in low-Fe-content films concentrated at the surface, near the film-substrate interface, at the edge of the films and at grain boundaries.

Magneto-optical properties of Ca-substituted Bi-YIG sputtered films

Ca-substituted Bi-YIG films (Bi 2 YFe 5-x Ca x O 12 , x=0.0, 0.3, 0.5, 1.0) were prepared by rf sputtering, and their magnetic and magneto-optical properties in the visible wavelength region were investigated. The films were deposited on Corning No. 7059 glass substrates at 400 o C. Sputter gas was Ar, 6.7 Pa, deposition rate 3.3 nm/min, rf-power density 2.5 W/cm 2

Transmission electron microscopy estimation of Bi–YIG nanoparticle hybridized with plastic material

We have developed a magneto-optical Bi1.8Y1.2Fe5O12 nanoparticle hybrid material and milling system. The Bi1.8Y1.2Fe5O12 nanoparticles were prepared with a coprecipitation and annealing processes. The 100 h milling nanoparticle system has θF about 1×103 degrees/cm but it has very small Ms (∼2.5 emu/cm3). In this material system, the particle size and crystalline size of the nanoparticles were estimated with a transmission electron microscope and transmission electron diffraction methods. The crystal phase sizes of the Bi1.8Y1.2Fe5O12 nanoparticles are the same as the nanoparticle sizes. The high-powered transmission electron microscope images show moire fringes of the nanoparticles. The 5–8 nm particles are primary nanoparticles. We show a possibility of the synthesis for the crystalline nanoparticles dispersed in hybrid materials by mechanical milling process.

Magnetic And Magneto-optical Properties Of Co-containing Bi-DyIG Particles Dispersed In A Plastic Binder

Nano-size Co/sub x/:BiDy/sub 2/Al/sub 0.8/Fe/sub 4.2/O/sub 12/ (0/spl les/x/spl les/2.0) particles were prepared with a coprecipitation method. The coating films of the particles were prepared with a coating technique. The magnetic and magneto-optical properties of the particles and films were investigated. The M/sub S/ and H/sub C/ of the particles and films increased with Co content, x. The Faraday rotation dropped with x. The x=0.5 film has high H/sub C/ about 450 Oe, and the figure of merit at 520 nm is about 0.63. The particle size in the film was about 50/spl sim/100 nm which is smaller than the wavelength of the read and write laser (633 nm). These results show that the coating Co/sub x/:BiDy/sub 2/Al/sub 0.8/Fe/sub 4.2/O/sub 12/ film is a candidate material for a new economical magneto-optical storage medium.

Magneto-optical properties of Bi-YIG nanoparticle with polymethacrylate matrix materials

In this paper, we will introduce hybridized materials constructed by the Bi-YIG nanoparticle and methacrylate (MA) monomer. We estimated the Bi-YIG nanoparticles dispersed properties with some derived MA materials used for plastic optical fiber. The magneto-optical properties of them are measured.

Development of Coating Materials of High Conductivity Ag layer for Electroplating Technologies

Nickel and/or Copper plated plastic materials are being used a lot in industrial and home use. Plating layer is added plastic molded items new functions protect against oxidization and scratch. In general, the plastic plating by electroplating is performed after the grant of a conductive substrate coating. The condition of this substrate coating has been known to significantly affect the plastic plating adhesion and durability. For example, the condition of the substrate coating is not good, its plating layer would have been easy to peel. In addition, more than half of the plastic plating process is a surface treatment as substrate coating, which increases the cost factor of Ni and/or Copper plating. We have developed a Silver mirror coating technology. Our Silver mirror coating, which has excellent gloss and high durability. In last years MRS 2011 spring meeting, we reported the development of the treatment materials to improve the durability of thin Silver mirror coating film. The new Improved materials supply high durability and strong adhesion to molding items. In this paper, we propose to use a thin electro-conducting film prepared with Silver mirror coating technology for plastics plating. We have a new plastic plating process with a Silver mirror layer. We tried to apply this technology to the base coating layer for plastic plating. The new process uses a thin plating of Silver reported in this paper, which can significantly shorten the plating process. Therefore, the new processes allow a very large cost savings and reduce environmental impact.