MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmiss...MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM）. The results show that the sample with 0.2% La3+（mass fraction） or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to （1.2%.） TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A·m2·kg-1) is lower than that of undoped (17.54 (A·m2·kg-1)) and it behaves superparamagnetically.展开更多
The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 ...The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 °C were systematically investigated.The dissolution property of high-ferrite gibbsitic bauxite is increased by increasing the dissolution temperature and the Na OH concentration or decreasing the particle size of bauxite,which is easy to dissolve under atmospheric pressure.The kinetic equations of gibbsitic bauxites with different ferrite contents during the dissolution process at different temperatures for different times were established,and the corresponding activation energies were calculated.The ferrite in the gibbsitic bauxite reduces the dissolution speed and increases the activation energy of dissolution,the diffusion process of which is the rate-controlling step.展开更多
文摘MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM）. The results show that the sample with 0.2% La3+（mass fraction） or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to （1.2%.） TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A·m2·kg-1) is lower than that of undoped (17.54 (A·m2·kg-1)) and it behaves superparamagnetically.
基金Projects(51104041,51174054,51374065)supported by the National Natural Science Foundation of ChinaProject(N130402010)supported by the Fundamental Research Funds for the Central Universities of China
文摘The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 °C were systematically investigated.The dissolution property of high-ferrite gibbsitic bauxite is increased by increasing the dissolution temperature and the Na OH concentration or decreasing the particle size of bauxite,which is easy to dissolve under atmospheric pressure.The kinetic equations of gibbsitic bauxites with different ferrite contents during the dissolution process at different temperatures for different times were established,and the corresponding activation energies were calculated.The ferrite in the gibbsitic bauxite reduces the dissolution speed and increases the activation energy of dissolution,the diffusion process of which is the rate-controlling step.
