Study of the microstructure and of the permeability spectra of Ni–Zn–Cu ferrites

Preparation of high-permeability NiCuZn ferrite

“…The two ferrites obviously showed relaxation resonance, with the real part µ′ decreasing drastically at high frequency of more than 1 MHz, because the spin rotation plays a relatively more important pole when the domain wall motion reduces. The frequency dispersion matches well with that reported in previous works (Caltun et al, 2002;Nakamura, 1997). Moreover, the ferrite sintered at 930 °C possesses higher permeability at 1 MHz and lower cut-off frequency than that sintered at 1200 °C.…”

“…However, conventional ceramic technique requires high sintering temperature of about 1200 °C which easily leads to the abnormal growth of grains and deterioration of the magnetic properties of the NiZn ferrite (Darko and Miha, 1999). So many new techniques were tried to reduce the sintering temperature of NiZn ferrite: such as addition of CuO and some sintering aids (Hsu et al, 1995;Seo and Oh, 1999;Shrotri et al, 1999;Lebourgeois, 2000;Caltun et al, 2002). New preparation methods, for instance sol-gel and co-precipitation methods, were also tried (Kim and Koh, 2003;Hsua et al, 2004;Anil Kumar et al, 1997).…”

Temperature Dependence of Initial Permeability of NixCo1-xFe2O4 Ferrite System

“…З точки зору практичного застосування, такі важливі параметри, як коерцитивна сила та магнітна проникність, не є властивостями самого ферриту, а залежать, окрім хімічного складу, також від різних дефектів і полікристалічної структури, тобто від форми та розмірів зерен і пор [4][5][6].…”

Effect of Sintering Time on the Structural, Magnetic and Electrical Transport Properties of Mg<sub>0.35</sub>Cu<sub>0.20</sub>Zn<sub>0.45</sub>Fe<sub>1.94</sub>O<sub>4</sub> Ferrites

“…The onset of the resonance frequency determines the upper limit of the operational frequency of any device. Moreover, the permeability values and hence the resonance frequency depend on the amount and type of dopantions, and the sintering condition of these samples [5,16]. In a typical Mg-ferrite, the resonance frequency was found to be at 50 MHz [17].…”