Development of Fine Crystal-Dispersed Transparent Materials for Optical Devices

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Through this study, we have established conditions for making fine particles of garnet ferrites with strong magneto-optical effect and for making transparent particulate films for optical applications in which the particles were dispersed into binder-matrix.Fine particles of Bi- and Ce-substituted iron garnet with average particle size as small as 50 nm were successfully prepared by coprecipitation and subsequent heat treatment. The particles had saturation magnetization and Faraday rotation about 0.6 times smaller than those of bulk garnet reported previously. Mossbauer spectroscopy revealed that this may be attributed to partial deficiencies of irons at tetrahedral sites.The magnetic inks in which the particles were homogeneously dispersed were obtained by not only coating the particle surfaces with a surfactant but also using sand-shaker on the dispersion process. The system of TiO_2-SiO_2 was found to be promising as a binder-matrix because it has high optical index and high stiffness which are required for reducing optical scattering and inducing high magnetic coercivity at the particles, respectively.Thus, we have, for the first time, obtained transparent particulate films having magnetization perpendicular to the film plane in which the garnet particles were dispersed into the binder-matrix.