The selected area electron diffraction （SAED） pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to...The selected area electron diffraction （SAED） pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.展开更多
Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-cont...Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-containing reagent is required.The temperature of 60 ℃,NaOH concentration of 0.10 mol/L;stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions.The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization.Magnetization kinetic equation is expressed as 1 [1(e0.269)]1/3 = Kt.Activation energy for the magnetization reaction is 4.30 kJ/mol.VSM,SEM and XPS were used to characterize the siderite,and results show that the saturated magnetization(rs) of siderite increased from 0.652 to 2.569Am2 /kg,the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization;Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4.展开更多
文摘The selected area electron diffraction （SAED） pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.
基金the financial support from the National Natural Science Foundation of China(No.51274256)
文摘Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-containing reagent is required.The temperature of 60 ℃,NaOH concentration of 0.10 mol/L;stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions.The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization.Magnetization kinetic equation is expressed as 1 [1(e0.269)]1/3 = Kt.Activation energy for the magnetization reaction is 4.30 kJ/mol.VSM,SEM and XPS were used to characterize the siderite,and results show that the saturated magnetization(rs) of siderite increased from 0.652 to 2.569Am2 /kg,the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization;Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4.
