J. Phys. IV France 07 (1997) C1-27-C1-30
Current Status of Soft Ferrite in JapanT. Ohiai
Materials Research Center, TDK Corporation, 570-2, Aza-matugasita, Minamihatori, Narita-shi, Chiba 286, Japan
This paper focuses on recent developments in the field of materials technology of soft ferrites in Japan. With the rapid development of the electronics market, the ferrite industry has grown to a considerable size. Magnetic characteristics of ferrites are quite sensitive to the chemical composition, the production process and to microstructure. Controlling these factors is an important key to achieving high performance ferrites. MnZn ferrites are classified according to their characteristics. High initial permeability materials are used for wide band and pulse transformers, and low power loss materials are used for power application. High initial permeability, over 20000 at 10kHz, was achieved by Bi2O3 addition using high purity raw materials. Low loss MnZn ferrite, with Pcv=199kW/m3 at 100kHz, has recently been developed by SnO2 addition under some optimized process conditions. NiCuZn ferrite is employed for multilayer-ferrite chip-components(MLFC). Low oxygen partial pressure during sintering is an important factor in controlling the nanostructure of grain boundaries. MnMgZn ferrite has been produced in large quantity for deflection yoke application because of its high cost performance. Investigation of composition, additives and sintering conditions has made it possible to obtain lower loss than that in NiCuZn ferrite measured at higher temperatures.
© EDP Sciences 1997