Developing Magneto-optical discs by applying new technology derrite platir

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1) Applying to magneto-optical memoty, wemust deposite magnetic film of good quality uniformly over a wide area of a disc as large as 8-12" in diameter. We have improved in this study ferrite plating methods to fit for this application. "Thin liquid filmmethod" and "spray spin-coating method" were invented, which facilitated formation of good-quality film uniformly over the whole area of an 8" disc.2) To save labor in experiment on sprey-spin coating method, which is the best one for prouducing magneto-optical discs, we have so chosen the pH values of reaction and oxidizing solutions that we dont need to use oxygen-free water. This facilitated mass production of magneto-optical disc by the ferrite plating.3) To reduce media noise in magneto-optical recording, we have found plating conditions on which film if good surface smoothness and small size is obtained. The film quality further improved by using a clean room and filters. Adding dextran or sucrose made the film smaller in grain size.4) By choosing value of x in Fe_<3-x> Co_xO_4, we can obtain coercive magnetic force fitted for magneto-optical disc in plated films of the solid solution spinel.5) Adhesion of the ferrite-plating film onto substrate of plastics such as acryl and polycarbonate (which are used for magneto-oprical discs) can be enhanced by exposing the surface of the substrate to an air plasma.