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이단하소에 의해 제조된 PNN-PZ-PN 세라믹의 압전 및 유전특성
이수호,손무헌,조현철,김한근,사공 건 東亞大學校 1997 東亞論叢 Vol.34 No.-
In the fields of the optics, precise machine, semiconductors, the micro-positioning actuators are required for the control of position in submicron range. PNN-PZN-PZT cermics were fabricated with various mole ratio of the PZT[Pb(Zr½ Ti½)O₃] PNN[Pb(Ni⅓Nb⅔)O₃]and PZN[Pb(Zn⅓Nb⅔)O₃]powders prepared by double calcination and PZT powders prepared by molten-salt synthesis method. The formation rate of perovskite phase in PNN-PZN-PZT ceramics could be obtained about 92% at PZT 0.3 mole ratio. The relative permittivity of specimen with PZT 0.3 mole ratio was shown 5,320 and appeared the relaxor ferroelectric feature. The maximum piezoelectric coefficient d₃₁to be used for evaluation the displacement of piezoceramics in PNN-PZN-PZT ceramics was 324×10¹²(C/V) at the vicinity of morphotropic phase boundary and was larger than that of solid PZT ceramics(120×10-¹²C/V).
合成溫度에 따른 濕式 Ni-Zn Ferrite 입자의 크기
金漢根,司空鍵 東亞大學校 1991 東亞論叢 Vol.28 No.1
Formation of Ni-Zn ferrite powders by wet direct method and its change of particle size dependent on the calcined temperature of the coprecipitates were examined. The coprecipitates were prepared by adding alkaline solution into the constituent metal ions solution, and subsequent heat treatments. At 150(℃ ), the particles were ultrafine spherical shaped particles of about 500(Å) in diameter and the particle size of Ni-Zn ferrite obtained by the wet direct method could be arranged from 700(Å) to 1450(Å) by changing the calcined temperature(400, 600, 700 and 1,000(℃ )) of the coprecipitates.
광대역형 Ferrite/Rubber 복합형 전파흡수체의 제작 및 특성
김한근,김삼룡,사공건 東亞大學校 1996 東亞論叢 Vol.33 No.-
In this paper, the microwave absorption properties of two layered absorber were evaluated. The two layer absorber were composed of Ni-Zn ferrite/rubber and Ferroxplana/rubber absorber. The excellent absorption properties of the two layered absorber were shown that the transforming layer was Ferroxplana/rubber absorber and the absorbing layer was Ni-Zn ferrite/ rubber absorber and that the optimal thickness of transforming and absorbing layer were 4 and 1(mm), respectively.
Ni-Zn Ferrite/Rubber복합형 전파흡수체의 정합조건 설계
김한근,사공건,신광호 東亞大學校 1994 東亞論叢 Vol.31 No.1
The demands for microwave absorbing materials and designs are being increased. We have studied about a new design technique to seek for the matching conditions for composite absorbers. The ferrite/rubber composite microwave absorbers were fabricated with Ni-Zn ferrite prepared by coprzcipitation method and silicone rubber. We have figured out the matching conditions(frequency and thickness) through the material constants of the self-maded ferrite/rubber composite absorber by utilizing the matching map and the matching boundary map. We could make a prediction for the matching conditions of ferrite/rubber composite absorber with our developed design technique.