Effect of the soft/hard exchange interaction on natural resonance frequency and electromagnetic wave absorption of the rare earth-iron-boron compounds

The effect of exchange interaction between the hard-magnetic Y2Fe14B and soft-magnetic Fe3B phases on the natural resonance phenomenon and microwave absorption properties was investigated. The Y2Fe14B/Fe3B ribbons were prepared by melt-spinning. The annealing at just above crystallization temperature of the ribbons and the Cu addition were effective to improve the exchange interaction between Y2Fe14B and Fe3B phases. A linear relationship between the recoil ratio and the shift of resonance frequency was confirmed. The Y9.4Fe79.3B11.1Cu0.2 ribbon, annealed at 1003 K, exhibited the largest recoil ratio of 0.49 and its resin composite showed the natural resonance frequency (f(r)) at 44 GHz, which was 23 GHz lower than that of the Y2Fe14B resin composite. The Y9.4Fe79.3B11.1Cu0.2 composite also exhibited good microwave absorption properties (over 99%) at 39.5 GHz with the absorber thickness of 0.38 mm. (C) 2004 Published by Elsevier B.V.