BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate （Ba（CH3COO2） and tetrabutyl titanate （Ti（OC4H9）4） as raw materials. Xerogel precursors and products were characterized by means of the...BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate （Ba（CH3COO2） and tetrabutyl titanate （Ti（OC4H9）4） as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry （TG/DSC）, X-ray diffraction （XRD） and transmission electron microscope （TEM）. The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.展开更多
The olivine-typed cathode material of Li Fe PO4 was prepared via sol-gel method,and the bromine was doped into Li Fe PO4.The crystal structure,morphology,and electrochemical properties of the samples were investigated...The olivine-typed cathode material of Li Fe PO4 was prepared via sol-gel method,and the bromine was doped into Li Fe PO4.The crystal structure,morphology,and electrochemical properties of the samples were investigated by X-ray diffraction,scanning electron microscopy and charge–discharge cycle measurements.The results showed that the electrochemical performance of Li Fe PO4 had been improved by bromine doping,and the best doping amount of bromine is 2%.The discharge capacity of this sample can reach 152 m Ah/g at 0.2 C.展开更多
文摘BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate （Ba（CH3COO2） and tetrabutyl titanate （Ti（OC4H9）4） as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry （TG/DSC）, X-ray diffraction （XRD） and transmission electron microscope （TEM）. The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.
文摘The olivine-typed cathode material of Li Fe PO4 was prepared via sol-gel method,and the bromine was doped into Li Fe PO4.The crystal structure,morphology,and electrochemical properties of the samples were investigated by X-ray diffraction,scanning electron microscopy and charge–discharge cycle measurements.The results showed that the electrochemical performance of Li Fe PO4 had been improved by bromine doping,and the best doping amount of bromine is 2%.The discharge capacity of this sample can reach 152 m Ah/g at 0.2 C.
