Cheng Yatong,Niu Yujuan,Xiang Feng,Chang Panpan,Wang Hong
Ba 3 Co 2 Fe 24 O 41 (Co 2 Z)/polyimide(PI) composites were synthesized via in-situ polymerization process, using the micron-sized Co 2 Z particles prepared by the solid-state reaction. X-ray diffractometer (XRD) pattern shows the existence and purity of the aimed phase. Scanning electron microscope (SEM) images show that the Co 2 Z particles are uniformly dispersed in the composites. The testing results of dielectric properties of composites reveal that the dielectric constants of the composites increase with the Co 2 Z content increasing. The frequency-dependent dielectric loss shows that the dielectric loss of samples has the same trend, and that a peak can be observed at about 10 MHz. The saturation magnetization (Ms) of composites depends on the ferrite content, and the Ms. value can reach 8.9 emu/g when the ferrite content is 40 wt% in Co 2 Z/PI composites. Additionally, the coercivity (Hc) of composites show almost no change as the ferrite content increasing, about 100 Oe. The results indicate that the obtained magnetic dielectric composites are new candidates for antenna applications.
Ning Shao,Juan Li,Shenglei Che,Jingwu Zheng,Liang Qiao,Yao Ying,Jing Yu,Wangchang Li
The L -band and S-band electromagnetic waves are widely utilized in radar and satellite communications. This paper reports the successful synthesis of 85.8% content Ba 3 Co 2 Fe 24 O 41 (Co 2 Z) at a relatively low temperature of 1150 °C using the solid-phase method with BaFe 12 O 19 (BaM) and Ba 2 Co 2 Fe 12 O 22 (Co 2 Y) as precursors. The Co 2 Z samples were confirmed to have been successfully synthesized using X-ray diffraction (XRD) and thermogravimetry/differential scanning calorimetry (TG-DSC) spectra. Scanning electron microscopy (SEM) images revealed that the sintered samples exhibited large grains (>10 µm). Vibrating-sample magnetometry (VSM) data indicated that the synthesized Co 2 Z samples possessed distinct soft magnetic properties . X-ray photoelectron spectroscopy (XPS) results showed that the Fe 3+ content decreased with the increase in synthesis temperature. The samples synthesized at 1110 °C − 1280 °C had a permeability of 10–20, a cut-off frequency of approximately 1 GHz, and a dielectric constant of 10–30. When the thickness of the sample synthesized at 1150 °C was 3.9 mm, the frequency range of the reflection loss (RL)< −10 dB was 2.55 GHz (0.98–3.53 GHz), with 1.77 GHz as the center frequency, and RLmin was − 57.8 dB. This observation indicates that the effective absorption bandwidth of the samples covers the entire L and S bands, which significantly satisfies practical applications within the military and civilian sectors.
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