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Compared with spherical ferromagnetic particles, flaky particles due to the higher permeability present great potentials as high-efficiency electromagnetic absorbing materials, especially in S band (2–4 GHz). FeSi flakes with different diameters were synthesized by ball-milling and subsequent screened processes, and hydrogen annealing and SiO2 coating were then utilized to further optimize the electromagnetic parameters for high-efficiency absorption. FeSi flakes with high diameter possess higher permittivity for the larger specific areas and higher permeability for the increased shape anisotropy. The decreased defects after annealing induce the reducing permittivity. The eddy current effect can be effectively suppressed after the SiO2 is coated on the surface of FeSi flakes. As for the coating containing 70 wt% FeSi@SiO2 flakes, the maximum reflection loss (RLmax) of –73 dB can be observed at 2.5 GHz with the coating thickness of 3 mm. Effective absorption band (ERL5, RL

Flake-shaped Fe–Si alloy particles with high aspect ratios were fabricated by ball milling commercially available Fe–Si powder, aiming to fabricate high-performance microwave absorbing fillers for coatings applied in 1–4 GHz range. To compare with spherical particles, higher permittivity and permeability was observed by using flaky particles as fillers. High aspect ratios contributed to an enhanced dielectric relaxation in the 1–4 GHz band, resulting in an increased permittivity. The thin thickness together with the high resistivity of Fe–Si flakes was believed to be helpful for suppressing the effect of eddy current and thus lead to an increase in the permeability. The electromagnetic wave absorbing (EMA) performances were observed to be enhanced. With a thin thickness of 2 mm, a wide absorption band with a minimum reflection loss of −12 dB was achieved in 1–4 GHz range, when using 75 wt% of flaky Fe–Si particles as fillers. The study indicated that flake-shaped Fe–Si particles were a promising candidate for EMA materials in L and S bands.

Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed.

C@FeNi3 core/shell structured microchains with an average diameter of 400 nm and lengths of about tens microns were synthesized by a simple hydrothermal method. The morphologies, microstructures and electromagnetic properties were investigated by means of scanning electron microscope, transmission electron microscopee, X-ray diffraction, Raman spectroscopy, physical property measurement system and vector network analyzer. C@FeNi3 core/shell structured microchains were constructed by FeNi3 alloy submicron spheres with average diameter of 350 nm and carbon shell with thickness about 50 nm. Their electromagnetic properties were investigated in the 2–18 GHz frequency range. The permittivity presented strong dielectric relaxation behavior over 11.5–18 GHz, corresponding to Debye dipolar relaxation. The permeability was found to have negative imaginary parts within 11.5–18 GHz. Strong dual-frequency absorption behavior was observed in the Ku-band due to consequence of interface relaxation.

Systematic studies of crystalline structure, magnetic and ferroelectric properties have been performed on polycrystalline Bi 0.8 La 0.2− x Pb x FeO 3 ceramic samples, in which x changes continuously from 0 to 0.2. Rietveld refinement of the x-ray diffraction (XRD) patterns shows that the compound crystal structure changes gradually from pseudotetragonal to pseudocubic with increasing Pb concentration. Coupled with the structural and compositional changes, magnetic ordering of the samples exhibits significantly non-monotonical variation corresponding to x . The compound remnant magnetization ( M r ) and coercivity ( H c ) both reach minimum values close to zero at x =0.07. This variation of magnetic property in co-doped samples can be attributed to the extent of suppression of cycloid spin structure in original BiFeO 3 with changing x . Unlike magnetic responses, the ferroelectric measurements show that the compounds have monotonical change in the remnant electric dipole polarization ( P r ).

The molten salt synthesis of sodium titanate one-dimensional nanostructures at relatively low temperature (ca. 825 °C) was re-examined in detail to elucidate the roles of various experimental parameters. Two kinds of sodium titanate nanowires, i.e., Na2Ti3O7 and Na2Ti6O13, with almost the same diameters were obtained in the presence of excess sodium oxalate, which also played an important role in enhancing nanowires yield. High calcining temperature favours the formation of Na2Ti6O13-predominant product at high sodium content. The introducing of nonionic surfactant NP-9 not only improves the uniformity of nanowires, but also favours the formation of Na2Ti6O13 phase. The obtained Na2Ti3O7 and Na2Ti6O13 nanowires have good crystallinity and both grow along the [010] crystallographic directions. The synthesized Na2Ti6O13 nanowires exhibited good photocatalytic activity towards the degradation of methyl orange under ultraviolet light irradiation. A humidity sensor based on Na2Ti3O7 nanowires was fabricated and showed good sensing performance at room temperature.

We presented, for the first time, the evidence of loop-by-loop self-coiling of a nanobelt to form single-crystal Na2Ti6O13 nanorings with diameters of several micrometres. The winding nanobelts, with thickness of about 15 nm and widths of 100–500 nm, grow along their [010] crystallographic directions, and coherently match at ±(200) crystallographic planes. The driving force of such a coherent match is suggested to be the minimization of local electrostatic energy introduced by the cations and anions. We also discussed the dependence of the nanoring's yield on the thickness of the nanobelts, which affects the elastic deformation energy and misfit energy of the rings.