Fuzhan Song

Magnetic hard/soft nanocomposite ferrite aligned hollow microfibers and remanence enhancement.

The nanocomposite SrFe(12)O(19)/Ni(0.5)Zn(0.5)Fe(2)O(4) ferrite aligned hollow microfibers with the hollow diameter to the fiber diameter estimated about 3/5 have been prepared by the gel precursor transformation process. The nanocomposite binary ferrites with different mass ratios are formed after the precursor calcined at 900°C for 2h, fabricating from SrFe(12)O(19) nanoparticles and Ni(0.5)Zn(0.5)Fe(2)O(4) nanoparticles with a uniform phase distribution. These nanocomposite ferrite microfibers show a combination of magnetic characteristics for the hard (SrFe(12)O(19)) and soft (Ni(0.5)Zn(0.5)Fe(2)O(4)) phase with an enhanced remanence owing to the exchange-coupling interactions. The aligned microfibers exhibit a shape anisotropy.

Fabrication and Magnetic Property of One-dimensional SrTiO3/SrFe12O19 Composite Nanofibers by Electrospinning

The composite nanofibers of SrTiO 3 /SrFe 12 O 19 with a molar ratio of 1:1 and diameter about 120 nm were prepared by electrospinning. Effects of calcination temperature on the formation, crystallite size, morphology and magnetic property were studied by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The binary phase of strontium ferrite and titanate was formed after being calcined at 900°C for 2 h and the composite nanofibers were fabricated from nanograins of SrTiC 3 about 24 nm and SrFe 12 O 19 around 33 nm. The crystallite sizes for the nanofibers increase with increasing calcination temperature and the addition of SrTiO 3 has an obvious suppression effect on SrFe 12 O 19 grain growth. The specific saturation magnetization and remanence tend to increase with the crystallite size. With increasing calcination temperature from 900 to 1050°C, the coercivity increases initially, achieving a maximum value of 520.2 kA·m −1 at 950°C, and then shows a reduction tendency.

Microwave absorbing characteristics of nanocrystalline Fe0.13(CoxNi100−x)0.87 alloy fine fiber–epoxy resin composites

The nanocrystalline Fe0.13(Co x Ni100− x )0.87 (x = 30, 50, and 80) alloy fiber 50 wt%–epoxy resin composites were prepared by mixing epoxy resin with the alloy fibers. The electromagnetic parameters of the composites were measured using the coaxial line method and the reflection loss was calculated at a frequency range 1–18 GHz. The results show that the nanocrystalline Fe0.13(Co x Ni100− x )0.87 alloy fiber–epoxy resin composites have effective microwave absorption characteristics in radar band, which are mainly influenced by the nanocrystalline alloy composition and the composite thickness. This microwave absorption effect largely arises from the eddy current, ferromagnetic resonance, and dielectric loss in the composite.