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URN etd-0708104-151940 Statistics This thesis had been viewed 2812 times. Download 842 times. Author Chia-hsiang Li Author's Email Address No Public. Department Materials Engineering Year 2003 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 100 Title Development of Ni-Mn ferrite for high frequency application Keyword second phase permeability ferrite ferrite permeability second phase Abstract In this study, Ni-Mn ferrites with different content of manganese, cobalt, and iron ions were prepared through conventional ceramic processing method. The specimens were sintered under various sintering conditions and atmosphere. The results showed that the μ’ and μ”max were increased slowly with the increase of the manganese ion content but the fm were decreased slowly with the increase of the manganese ion content. The μ’ and μ”max were decreased and the resonance frequencies were increased with the increase of the cobalt or iron ion content. Incorporation of the cobalt ions into the ferrites can enhance the resonance frequency by changing its anisotropy. In other words, the contribution of cobalt ions was increasing the domain-wall stabilization. The effects of excessive iron ions were present when the granular α-Fe2O3 second phase particles were formed in the matrix to hinder the domain wall motion. Grain growth, occurred at high temperature, and formation of the second phase, occurred at low temperature, are in competition. The grain growth could be inhibited by the presence of the second phase. Thus, second phase and doping the cobalt ions are effective ways in the manufacturing of ferrite materials for high frequency applications. Advisor Committee Wan-Yi Wei - advisor
Chih-Wen Hsieh - co-chair
Hur-Lon Lin - co-chair
Files Date of Defense 2004-05-24 Date of Submission 2004-07-08