Magnesium-substituted Mn0.8Zn0.2Fe2O4 ferrite is synthesized by the sol–gel combustion method using citrate acid as the complex agent. The electromagnetic absorbing behaviors of ferrite/polymer coatings fabricated by...Magnesium-substituted Mn0.8Zn0.2Fe2O4 ferrite is synthesized by the sol–gel combustion method using citrate acid as the complex agent. The electromagnetic absorbing behaviors of ferrite/polymer coatings fabricated by dispersing Mn–Zn ferrite into epoxy resin （EP） are studied. The microstructure and morphology are characterized by X-ray diffraction and scanning electron microscope. Complex permittivity, complex permeability, and reflection loss of ferrite/EP composite coating are investigated in a low frequency range. It is found that the prepared ferrite particles are traditional cubic spinel ferrite particles with an average size of 200 nm. The results reveal that the electromagnetic microwave absorbing properties are significantly influenced by the weight ratio of ferrite to polymer. The composites with a weight ratio of ferrite/polymer being 3：20 have a maximum reflection loss of –16 dB and wide absorbing band. Thus, the Mn–Zn ferrite is the potential candidate in electromagnetic absorbing application in the low frequency range （10 MHz–1 GHz）.展开更多
Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environ...Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.展开更多
Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long...Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long been overlooked,impeding broadening of the ultra-broadband EM wave absorption performance in heterostructures.Herein,via surface ligand modulation,in situ growth of 0D Fe_(3)O_(4)quantum dots(QDs)on the surface of 1D carbon nanotubes triggers grain boundary coupling.The energy rebalancing effect at the interface induces an extreme charge rearrangement within the Fe_(3)O_(4)QDs.This rearrangement enhances dipole orientation hysteresis and charge accumulation,resulting in charge and interfacial polarization losses.Meanwhile,for subcritical Fe_(3)O_(4)QDs,short-range magnetic resonance and magnetic exchange-triggered magnetic resonance transfer synergistically enhance the magnetic loss.Through charge rearrangement/magnetic resonance induced by0D/1D grain boundary coupling,an effective bandwidth of nearly 10 GHz is achieved at a minimal thickness of 2 mm,covering the X and Ku bands.This strategy provides an effective paradigm and novel theoretical insights for ultra-broadband electromagnetic wave absorption applications.展开更多
Thermal sensitive MnZn ferrite is a kind of soft magnetic ferrite material with lower Curie temperature (Tc) and can be used to make many kinds of magnetic thermal sensitive sensors with high sensitivity. In this pape...Thermal sensitive MnZn ferrite is a kind of soft magnetic ferrite material with lower Curie temperature (Tc) and can be used to make many kinds of magnetic thermal sensitive sensors with high sensitivity. In this paper, the relation between the composition of thermal sensitive ferrite and TC was studied. It was found that TC changes linearly with ZnO extent when the content of Fe2O3 is fixed. Based on lots of experiments, an experimential formula to determine was given out.展开更多
The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel （FSS）/carbon steel （CS） laminate was investigated. The results indicate tha...The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel （FSS）/carbon steel （CS） laminate was investigated. The results indicate that by hot rolling, decarburization layer disappears and a uniform structure is gained in CS side, but ferrite grains and carbides in constituent FSS form an uneven band microstructure which is denser at superficial zone than near the interface. The transmission electron microscopy results indicate that the layers adhering to the interface show typical deformed microstructure features, i.e., stream-like strips and elongated grains in FSS plates, carbide precipitates and bended cementite fragments in CS plates; and high-density dislocations in both plates, With hot rolling, various mechanical strengths and hardness are increased, while the elongation percentage is diminished. Examination of fractographs from tensile tests reveals predominately small dimples for explosive-welded specimens, whereas both big dimples and cleavage fracture for rolled specimens. Stereomicroscopic fractographs taken on shear samples indicate that the surfaces of explosive-welded specimens exhibit uniform deformation, but uneven deformation is displayed for that of rolled specimens. These results indicate that hot rolling is beneficial to improve the strength of explosive-welded FSS/CS laminate but not good for enhancing its plasticity.展开更多
基金Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20121101110014)
文摘Magnesium-substituted Mn0.8Zn0.2Fe2O4 ferrite is synthesized by the sol–gel combustion method using citrate acid as the complex agent. The electromagnetic absorbing behaviors of ferrite/polymer coatings fabricated by dispersing Mn–Zn ferrite into epoxy resin （EP） are studied. The microstructure and morphology are characterized by X-ray diffraction and scanning electron microscope. Complex permittivity, complex permeability, and reflection loss of ferrite/EP composite coating are investigated in a low frequency range. It is found that the prepared ferrite particles are traditional cubic spinel ferrite particles with an average size of 200 nm. The results reveal that the electromagnetic microwave absorbing properties are significantly influenced by the weight ratio of ferrite to polymer. The composites with a weight ratio of ferrite/polymer being 3：20 have a maximum reflection loss of –16 dB and wide absorbing band. Thus, the Mn–Zn ferrite is the potential candidate in electromagnetic absorbing application in the low frequency range （10 MHz–1 GHz）.
文摘Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.
基金supported by The Youth Innovation Team of Shaanxi Universities and The Innovation and Entrepreneurship Team of Special Support Program for‘Sanqin’Talentthe Special Support Program for High-level Talents of Shaanxi Province(No.2020-44)the China Postdoctoral Science Foundation(2022M723884)。
文摘Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long been overlooked,impeding broadening of the ultra-broadband EM wave absorption performance in heterostructures.Herein,via surface ligand modulation,in situ growth of 0D Fe_(3)O_(4)quantum dots(QDs)on the surface of 1D carbon nanotubes triggers grain boundary coupling.The energy rebalancing effect at the interface induces an extreme charge rearrangement within the Fe_(3)O_(4)QDs.This rearrangement enhances dipole orientation hysteresis and charge accumulation,resulting in charge and interfacial polarization losses.Meanwhile,for subcritical Fe_(3)O_(4)QDs,short-range magnetic resonance and magnetic exchange-triggered magnetic resonance transfer synergistically enhance the magnetic loss.Through charge rearrangement/magnetic resonance induced by0D/1D grain boundary coupling,an effective bandwidth of nearly 10 GHz is achieved at a minimal thickness of 2 mm,covering the X and Ku bands.This strategy provides an effective paradigm and novel theoretical insights for ultra-broadband electromagnetic wave absorption applications.
基金National Natural Science Foundation of China!(No. 59972011).
文摘Thermal sensitive MnZn ferrite is a kind of soft magnetic ferrite material with lower Curie temperature (Tc) and can be used to make many kinds of magnetic thermal sensitive sensors with high sensitivity. In this paper, the relation between the composition of thermal sensitive ferrite and TC was studied. It was found that TC changes linearly with ZnO extent when the content of Fe2O3 is fixed. Based on lots of experiments, an experimential formula to determine was given out.
基金This research was funded by the National Natural Science Foundation of China under Grant No. U 1510131, the Key Research and Development Program of Shanxi Province under Grant Nos. 201603D121010 and 201603D111004 and Shanxi Young Scholars Program.
文摘The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel （FSS）/carbon steel （CS） laminate was investigated. The results indicate that by hot rolling, decarburization layer disappears and a uniform structure is gained in CS side, but ferrite grains and carbides in constituent FSS form an uneven band microstructure which is denser at superficial zone than near the interface. The transmission electron microscopy results indicate that the layers adhering to the interface show typical deformed microstructure features, i.e., stream-like strips and elongated grains in FSS plates, carbide precipitates and bended cementite fragments in CS plates; and high-density dislocations in both plates, With hot rolling, various mechanical strengths and hardness are increased, while the elongation percentage is diminished. Examination of fractographs from tensile tests reveals predominately small dimples for explosive-welded specimens, whereas both big dimples and cleavage fracture for rolled specimens. Stereomicroscopic fractographs taken on shear samples indicate that the surfaces of explosive-welded specimens exhibit uniform deformation, but uneven deformation is displayed for that of rolled specimens. These results indicate that hot rolling is beneficial to improve the strength of explosive-welded FSS/CS laminate but not good for enhancing its plasticity.
