Differences of the morphology and nanostructure evolution of incipient soot particles generated in n-heptane/2,5-dimethylfuran(DMF)inverse diffusion flames(IDFs)with/without magnetic fields were investigated.Utilizing...Differences of the morphology and nanostructure evolution of incipient soot particles generated in n-heptane/2,5-dimethylfuran(DMF)inverse diffusion flames(IDFs)with/without magnetic fields were investigated.Utilizing a high resolution transmission electron spectroscopy,the morphology and nanostructures of soot sampled from spatial locations at different heights in IDFs were analyzed.The graphitization and the oxidation reactivity of soot were tested by an X-ray diffraction and a thermogravimetric analyzer,respectively.Results demonstrated that the magnetic force on paramagnetic species,such as oxygen molecules,can modify the soot formation and oxidation.More incipient soot particles with larger diameters appeared in chains or branches or tufted forms on the flame wing region and the higher position than that on the flame centerline region and the lower position.With magnetic fields,greater amounts of clustered soot particles displayed more crowded distribution and larger diameters.Soot particles with typical structures of the core-shell were promoted to own more orderly bordered lamellae with longer fringe length and smaller fringe tortuosity by the magnetic force acting on oxygen at the same sample position.These modifications resulted in relatively larger diffraction angle of the peak,higher graphitization degree and slightly lower oxidation reactivity of soot.展开更多
Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and ...Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties. Finally, the prepared magnetic composite particles latex is stable for several months.展开更多
The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.Accor...The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.According to the low density system of magnetic colloidal particles in water,a theoretic model is set up based on perturbation theory.The relations between internal energy,specific heat of magnetic colloidal particles system and temperature,density of colloidal particles are calculated.The calculated results are useful in explaining the magnetic memory effect.展开更多
This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction....This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite （α-FeOOH） to magnetite （Fe3O4）, and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.展开更多
基金supported by the National Natural Science Foundation of China(51822605,51706103,51776181)the Fundamental Research Funds for the Central Universities(ZJUCEU2017011,CEPE2019010)。
文摘Differences of the morphology and nanostructure evolution of incipient soot particles generated in n-heptane/2,5-dimethylfuran(DMF)inverse diffusion flames(IDFs)with/without magnetic fields were investigated.Utilizing a high resolution transmission electron spectroscopy,the morphology and nanostructures of soot sampled from spatial locations at different heights in IDFs were analyzed.The graphitization and the oxidation reactivity of soot were tested by an X-ray diffraction and a thermogravimetric analyzer,respectively.Results demonstrated that the magnetic force on paramagnetic species,such as oxygen molecules,can modify the soot formation and oxidation.More incipient soot particles with larger diameters appeared in chains or branches or tufted forms on the flame wing region and the higher position than that on the flame centerline region and the lower position.With magnetic fields,greater amounts of clustered soot particles displayed more crowded distribution and larger diameters.Soot particles with typical structures of the core-shell were promoted to own more orderly bordered lamellae with longer fringe length and smaller fringe tortuosity by the magnetic force acting on oxygen at the same sample position.These modifications resulted in relatively larger diffraction angle of the peak,higher graphitization degree and slightly lower oxidation reactivity of soot.
文摘Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties. Finally, the prepared magnetic composite particles latex is stable for several months.
文摘The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.According to the low density system of magnetic colloidal particles in water,a theoretic model is set up based on perturbation theory.The relations between internal energy,specific heat of magnetic colloidal particles system and temperature,density of colloidal particles are calculated.The calculated results are useful in explaining the magnetic memory effect.
文摘This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite （α-FeOOH） to magnetite （Fe3O4）, and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.
