The microstructure and performance of Li4Ti5O12 doped by Mg prepared by hydrothermal method and solid phase method were investigated. Lithium dihydrate, magnesium acetate and tetrabutyl titanate were used as the main ...The microstructure and performance of Li4Ti5O12 doped by Mg prepared by hydrothermal method and solid phase method were investigated. Lithium dihydrate, magnesium acetate and tetrabutyl titanate were used as the main raw materials. This study reveals that Mg^2+ has influences on the spherical structure, crystal development of Li4Ti5O12 and the electrochemical performances. The hollow spherical structure is composed of nano-sheet structure and the nano-sheet structure can be affected by the Mg^2+ content. For Li4-xMgxTi5 O12, the sheet structure can be refined with the increment of Mg^2+ content when x value is 0-0.1 and coarsen with the increment of Mg^2+ content when x value is 0.1-0.2. The hollow spherical Li4Ti5O12 powders prepared by hydrothermal method have better performance. The optimal Mgdoped amount of hydrothermal method is 0.1. At 0.1 C, the first discharge capacity of Li3.9Mg0.1Ti5O12 prepared through hydrothermal method at 0.1 C and 10 cycles is 182 and 178 mA hg^-1, respectively.展开更多
Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical S...Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.展开更多
The α-Fe_2 O_3@SiO_2 reddish pigments with core-shell structure were successfully prepared by hydrothermal and Stober methods. The structure, morphology, and chromaticity of the synthesized pigments were characterize...The α-Fe_2 O_3@SiO_2 reddish pigments with core-shell structure were successfully prepared by hydrothermal and Stober methods. The structure, morphology, and chromaticity of the synthesized pigments were characterized by XRD, SEM, TEM, FTIR, XPS, and colorimetry. The results indicated that the as-prepared pigments have the characteristics of narrow particle size distribution, high dispersion,and good sphericity. The α-Fe_2 O_3@SiO_2 reddish pigments were uniform and well dispersed in solution. In addition, the pigments with different shell thickness were also prepared, and the effect of shell thickness on the color performance of the pigments was discussed.展开更多
基金Funded by the National Natural Science Foundation of China(No.51072162).
文摘The microstructure and performance of Li4Ti5O12 doped by Mg prepared by hydrothermal method and solid phase method were investigated. Lithium dihydrate, magnesium acetate and tetrabutyl titanate were used as the main raw materials. This study reveals that Mg^2+ has influences on the spherical structure, crystal development of Li4Ti5O12 and the electrochemical performances. The hollow spherical structure is composed of nano-sheet structure and the nano-sheet structure can be affected by the Mg^2+ content. For Li4-xMgxTi5 O12, the sheet structure can be refined with the increment of Mg^2+ content when x value is 0-0.1 and coarsen with the increment of Mg^2+ content when x value is 0.1-0.2. The hollow spherical Li4Ti5O12 powders prepared by hydrothermal method have better performance. The optimal Mgdoped amount of hydrothermal method is 0.1. At 0.1 C, the first discharge capacity of Li3.9Mg0.1Ti5O12 prepared through hydrothermal method at 0.1 C and 10 cycles is 182 and 178 mA hg^-1, respectively.
基金supported by the National Basic Research Program of China (Grant No.2007CB613603)
文摘Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.
基金financially supported by the Initiative Scientific Research Program from Jingdezheng Ceramic Institute and SRT Program (No. 1721T0264) from Tsinghua University
文摘The α-Fe_2 O_3@SiO_2 reddish pigments with core-shell structure were successfully prepared by hydrothermal and Stober methods. The structure, morphology, and chromaticity of the synthesized pigments were characterized by XRD, SEM, TEM, FTIR, XPS, and colorimetry. The results indicated that the as-prepared pigments have the characteristics of narrow particle size distribution, high dispersion,and good sphericity. The α-Fe_2 O_3@SiO_2 reddish pigments were uniform and well dispersed in solution. In addition, the pigments with different shell thickness were also prepared, and the effect of shell thickness on the color performance of the pigments was discussed.
