The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± ...The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.展开更多
Spindle-shaped anatase TiO2 secondary particles were successfully fabricated via the oriented attachment of primary nanocrystals. By adjusting the concentration of tetrabutyl titanate, the size of the TiO2 nanocrystal...Spindle-shaped anatase TiO2 secondary particles were successfully fabricated via the oriented attachment of primary nanocrystals. By adjusting the concentration of tetrabutyl titanate, the size of the TiO2 nanocrystals and particles could be controlled, resulting in pore evolution. Pores for the random aggregation of secondary particles gradually transformed to nanopores originating from the oriented attachment of the primary nanocrystals, resulting in an excellent micro/nanostructure that increased the performance of a sodium-ion battery. The mesoporous TiO2 microparticle anode, with its unique combination of nanocrystals and uniform nanopores, displays super durability （95 mAh/g after 11,000 cycles at I C）, high initial efficiency （61.4%）, and excellent rate performance （265 and 77 mAh/g at 0.1 and 20 C, respectively）. In particular, at slow discharge （0.1 C） and fast charge （5, 50, and 100 C） rates, the anatase TiO2 shows remarkable initial charge capacities of 200, 119, and 56 mAh/g, corresponding to 172, 127, and 56 mAh/g, after 150 cycles, respectively, thus meeting the requirements for fast energy storage. This excellent performance can be attributed to the stability of the material and its high ionic conductivity, resulting from the stable architecture with a mesoporous microstructure and without the random aggregation of secondary particles. A fundamental understanding of the pore structure and controllable pore construction has been proven to be effective in increasing the rate capability and durability of nanostructured electrode materials.展开更多
文摘The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.
文摘Spindle-shaped anatase TiO2 secondary particles were successfully fabricated via the oriented attachment of primary nanocrystals. By adjusting the concentration of tetrabutyl titanate, the size of the TiO2 nanocrystals and particles could be controlled, resulting in pore evolution. Pores for the random aggregation of secondary particles gradually transformed to nanopores originating from the oriented attachment of the primary nanocrystals, resulting in an excellent micro/nanostructure that increased the performance of a sodium-ion battery. The mesoporous TiO2 microparticle anode, with its unique combination of nanocrystals and uniform nanopores, displays super durability （95 mAh/g after 11,000 cycles at I C）, high initial efficiency （61.4%）, and excellent rate performance （265 and 77 mAh/g at 0.1 and 20 C, respectively）. In particular, at slow discharge （0.1 C） and fast charge （5, 50, and 100 C） rates, the anatase TiO2 shows remarkable initial charge capacities of 200, 119, and 56 mAh/g, corresponding to 172, 127, and 56 mAh/g, after 150 cycles, respectively, thus meeting the requirements for fast energy storage. This excellent performance can be attributed to the stability of the material and its high ionic conductivity, resulting from the stable architecture with a mesoporous microstructure and without the random aggregation of secondary particles. A fundamental understanding of the pore structure and controllable pore construction has been proven to be effective in increasing the rate capability and durability of nanostructured electrode materials.
