Preparation and Characteristics of a Magnetic-Dielectric (F3O4/ BaTiO3) Composite by Ferrite Plating with Ultrasound Irradiation

초록

There has been a great of interest on magnetic composites. Recently, magnetic composites have been reported in the ferrite-forsterite and ferrite-cordierite systems, which exhibit considerable changes in properties [1, 2]. However, such composites require usually high temperature for crystallization of ferrite. Ferrite plating with ultrasound irradiation enables formation of ferrite films directly on substrates of various shapes at low temperatures (60~100℃). Fe3O4-encapsulation was performed on BaTiO3 powder with grain size of 500 ㎚ using ultrasound en-hanced ferrite plating to prepare a magnetic-dielectric composite powder. The effect of the plating condi-tions on the formation of Fe3O4 was investigated and the optimum plating conditions were determined [3]. The Fe3O4/BaTiO3 composite powder exhibited Fe3O4 grains deposited densely on the surface of the BaTiO3 powder. In this study, comparative microwave absorbing measurements was performed on Fe3O4, Fe3O4/BaTiO3 mixed, synthesized Fe3O4/BaTiO3 composite and BaTiO3 specimens, The results showed that the match-ing frequency of those specimens of the same thickness shifted to higher frequency in sequence, com-pared to that of the BaTiO3 one. In sintered Fe3O4/BaTiO3 composite powder, the nanosized coated Fe3O4 grains helped a low temperature sintering of Fe3O4/BaTiO3 composite at a much lower tempera-ture, compared to the sintering temperature of the pure BaTiO3, The sintered Fe3O4/BaTiO3 composite revealed a large magneto-electric properties, simultaneously. This work was supported by Korea Research Foundation Grant (KRF-2001-005-E20008). References [1] H. Y. Luo, Z. X. Yue, J. Zhou, J. Magn. Magn. Mater. 210, 104 (2000). [2] Z. Yue, L. Li, J. Zhou, H. Zhang, Z. Ma, Z. Gui, Mater. Lett. 44, 279 (2000). [3] S. H. Choi, J. H. Oh, T. Ko, J. Magn. Magn. Mater. in press (2003).