The surface of as-prepared LiMn2O4 was modified with ZnO, Al2O3, CoO and LiCoO2 using a simple nitrate melting impregnation method. Transmission electron microscopy （TEM） studies indicated that oxide nano- particles...The surface of as-prepared LiMn2O4 was modified with ZnO, Al2O3, CoO and LiCoO2 using a simple nitrate melting impregnation method. Transmission electron microscopy （TEM） studies indicated that oxide nano- particles in the range of 10～50 nm are coated on the surface of the spinel. The surface modified samples show better capacity retention than the unmodified LiMn2O4 spinel at both room temperature and 55℃. Among these samples, the ZnO-modified LiMn2O4 shows the best combination of a high capacity and a low capacity fading rate of 0.036% per cycle at room temperature and 0.064% per cycle at 55℃. The improvement for surface modified LiMn2O4 can be attributed to the inhibition of Mn dissolution and O losses on the surface.展开更多
This paper reports that Nd2O3 nanoparticles modified by AOT（sodium bis（2-ethylhexyl） sulfosuccinate） were prepared using microemulsion method in the system of water and propanol/AOT/toluene. Transmission electron ...This paper reports that Nd2O3 nanoparticles modified by AOT（sodium bis（2-ethylhexyl） sulfosuccinate） were prepared using microemulsion method in the system of water and propanol/AOT/toluene. Transmission electron microscopy shows that the Nd2O3 nanoparticles take the shape of sphere with 18 nm and 31 nm with different preparation. The organic sol of Nd2O3 nanoparticles is very stable at room temperature. X-ray diffraction results show that the product has hexagonal phase structure. Two ultraviolet emission band at 344 nm and 361 nm corresponding to the transition of ^4 D3/2→4 I9/2 and 2P3/2→^4I 11/2 or ^4D 3/2→ ^4 I 13/2 were observed.展开更多
Modified lithium manganese oxides were prepared by solid-state reaction of LiMn2O4 and LiCoO2 as raw materials. A study was carried out by TG-DSC, XRD, DSC and electrochemical to analyse the reaction process and struc...Modified lithium manganese oxides were prepared by solid-state reaction of LiMn2O4 and LiCoO2 as raw materials. A study was carried out by TG-DSC, XRD, DSC and electrochemical to analyse the reaction process and structural characterization of products. The results show that the LiMn2O4 reacts chemically with LiCoO2 at high temperature. All of Li and partial Co atoms can insert into the LiMn2O4 crystal lattice and a newly formed spinel phase-modified LiMn2O4 was obtained. The distribution of Co content is even in modified LiMn2O4 compound. The modified LiMn2O4 compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn2O4.展开更多
For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different proces...For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different processing time. Breaking force and water contact angle were tested. Surface changes before and after surface modifications were tested with scanning electron microscopy(SEM). Furthermore,differential scanning calorimeter(DSC) and Fourier transform infrared spectrometry(FTIR) were used to analyze the changes of molecular structure and functional group. Experimental results showed that 6 min was the most suitable time for improving hydrophilicity of PGA filament and preserving its mechanical properties.展开更多
Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strengt...Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strength as the same time. PGA fibers are dipped in H_2O_2 solution a certain time for modification. Scanning electron microscopy( SEM) was used to observe the surface morphology of PGA fibers before and after modification. The varying of PGA macromolecule was examined with Fourier transform infrared spectroscopy( FTIR) analyses. X-ray diffraction( XRD) and differential scanning calorimetry( DSC) analysis showed that crystallinity slightly decreases. Mechanical performance test showed tensile force of modified PGA fiber was increased. The water contact angle test indicated the improving of hydrophilic. A cell proliferation assay showed that fibroblast cells attach and proliferate well on the fibers, which meant the modified fibers possess good cytocompatibility. These results suggest that H_2O_2 surface modification is easy to operate and a advantageous modification method for PGA fibers.展开更多
To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffract...To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction （ XRD ）, X-ray photoelectron spectroscopy （ XPS ） and scanning electron microscopy （SEM）. The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer （ Zsimpwin ） combined with a potentiostate （ PAR 273）. Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.展开更多
In order to improve the cycle performance of LiMn2O4, the modified LiMn,O4 was prepared by solid-state reactions using LiMn2O4 and LiCoO2 as precursors. XRD and EDS were used to study the structure properties of the m...In order to improve the cycle performance of LiMn2O4, the modified LiMn,O4 was prepared by solid-state reactions using LiMn2O4 and LiCoO2 as precursors. XRD and EDS were used to study the structure properties of the modified LiMn2O4. The electrochemical properties of the modified LiMn2O4 were also investigated. The results show that Li and Co atoms could insert into the LiMn2O4crystal lattice and a newly formed spinel phase, modified LiMn2O4 was obtained. The modified LiMn2O4 exhibits excellent cycle ability at room and elevated temperatures compared to pure LiMn2O4. The improved electrochemical stability of the modified LiMn2O4 attributes to the entrance of Li and Co ions inserted into the spinel crystal structure.展开更多
Modified lithium manganese oxides were prepared by using LiMn 2 O 4 and LiCoO 2 as precursors by solid state reaction.A study has been carried out by TG - DSC,XRD and FTIR to analyze the reaction process and structura...Modified lithium manganese oxides were prepared by using LiMn 2 O 4 and LiCoO 2 as precursors by solid state reaction.A study has been carried out by TG - DSC,XRD and FTIR to analyze the reaction process and structural characterization of products.The results showed that the LiMn 2 O 4 reacted chemically with LiCoO 2 at high temper - ature.Li and Co atom could insert into the LiMn 2 O 4 crystal lattice and obtained the Cobalt - Doped spinel com - pound.The results of constant - current cyclic test showed that the cyclic stability of the products are increased with the amount of doped LiCoO 2 ,while their initial capacity is decreased.展开更多
The ultra-high molecular mass polyethylene (UHMMPE) as an artificial joint acetabular material was filled with nano-powder of Al2O3 of various mass fractions. The effect of Al2O3 mass fraction on the hardness, wetting...The ultra-high molecular mass polyethylene (UHMMPE) as an artificial joint acetabular material was filled with nano-powder of Al2O3 of various mass fractions. The effect of Al2O3 mass fraction on the hardness, wetting property and tribological properties of the Al2O3-UHMMPE composites under dry friction sliding against both stainless steel and Ti-6Al-4V alloy was investigated. The morphologies of the worn surfaces of composites were observed with optical microscope. The results show that, wetting property and wear resistance of the composites are improved by filling Al2O3, while the friction coefficient is decreased largely under dry friction as compared with that of the unfilled UHMMPE. This is attributed to the reinforcing function of the nano-powder of Al2O3 in the composites. The wear of UHMMPE is dominated by plowing, plastic deformation and fatigue wear; while the Al2O3-UHMMPE composites are characterized by the mild fatigue wear.展开更多
通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后...通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后复合材料的带隙减小,光生载流子复合率大幅下降,当Bi_(2)S_(3)循环5次时,TiO_(2)纳米复合材料的光电化学性能最好。带隙减小到2.9 e V,光电流密度由改性前的200μA·cm^(-2)提升至550μA·cm^(-2),是改性前的2.75倍;将其与304不锈钢耦合后,电位降至-1.0 V,比改性前的耦合电位低80 m V,可以进一步提升对304不锈钢的光生阴极保护效果。展开更多
文摘The surface of as-prepared LiMn2O4 was modified with ZnO, Al2O3, CoO and LiCoO2 using a simple nitrate melting impregnation method. Transmission electron microscopy （TEM） studies indicated that oxide nano- particles in the range of 10～50 nm are coated on the surface of the spinel. The surface modified samples show better capacity retention than the unmodified LiMn2O4 spinel at both room temperature and 55℃. Among these samples, the ZnO-modified LiMn2O4 shows the best combination of a high capacity and a low capacity fading rate of 0.036% per cycle at room temperature and 0.064% per cycle at 55℃. The improvement for surface modified LiMn2O4 can be attributed to the inhibition of Mn dissolution and O losses on the surface.
基金Project supported by State Key Project of Fundamental Research for Nanoscience and Nanotechnology (Grant No 2006CB932300)the National Natural Science Foundation of China (Grant No 50725208)
文摘This paper reports that Nd2O3 nanoparticles modified by AOT（sodium bis（2-ethylhexyl） sulfosuccinate） were prepared using microemulsion method in the system of water and propanol/AOT/toluene. Transmission electron microscopy shows that the Nd2O3 nanoparticles take the shape of sphere with 18 nm and 31 nm with different preparation. The organic sol of Nd2O3 nanoparticles is very stable at room temperature. X-ray diffraction results show that the product has hexagonal phase structure. Two ultraviolet emission band at 344 nm and 361 nm corresponding to the transition of ^4 D3/2→4 I9/2 and 2P3/2→^4I 11/2 or ^4D 3/2→ ^4 I 13/2 were observed.
文摘Modified lithium manganese oxides were prepared by solid-state reaction of LiMn2O4 and LiCoO2 as raw materials. A study was carried out by TG-DSC, XRD, DSC and electrochemical to analyse the reaction process and structural characterization of products. The results show that the LiMn2O4 reacts chemically with LiCoO2 at high temperature. All of Li and partial Co atoms can insert into the LiMn2O4 crystal lattice and a newly formed spinel phase-modified LiMn2O4 was obtained. The distribution of Co content is even in modified LiMn2O4 compound. The modified LiMn2O4 compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn2O4.
基金Shanghai Municipality Science and Technology Commission,China(No.12DZ1940300)
文摘For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different processing time. Breaking force and water contact angle were tested. Surface changes before and after surface modifications were tested with scanning electron microscopy(SEM). Furthermore,differential scanning calorimeter(DSC) and Fourier transform infrared spectrometry(FTIR) were used to analyze the changes of molecular structure and functional group. Experimental results showed that 6 min was the most suitable time for improving hydrophilicity of PGA filament and preserving its mechanical properties.
基金Shanghai Science and Technical Committee,China(No.10411953300)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,China(No.LZ0902)Minhang District Industry-Study-Research Cooperation,China(No.2012MH202)
文摘Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strength as the same time. PGA fibers are dipped in H_2O_2 solution a certain time for modification. Scanning electron microscopy( SEM) was used to observe the surface morphology of PGA fibers before and after modification. The varying of PGA macromolecule was examined with Fourier transform infrared spectroscopy( FTIR) analyses. X-ray diffraction( XRD) and differential scanning calorimetry( DSC) analysis showed that crystallinity slightly decreases. Mechanical performance test showed tensile force of modified PGA fiber was increased. The water contact angle test indicated the improving of hydrophilic. A cell proliferation assay showed that fibroblast cells attach and proliferate well on the fibers, which meant the modified fibers possess good cytocompatibility. These results suggest that H_2O_2 surface modification is easy to operate and a advantageous modification method for PGA fibers.
基金Funded by Guangdong Provincial Natural Science Foundation ofChina(No.06300397) and Director Foundation of South China Ag-ricultural University (No.K06143)
文摘To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction （ XRD ）, X-ray photoelectron spectroscopy （ XPS ） and scanning electron microscopy （SEM）. The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer （ Zsimpwin ） combined with a potentiostate （ PAR 273）. Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.
文摘In order to improve the cycle performance of LiMn2O4, the modified LiMn,O4 was prepared by solid-state reactions using LiMn2O4 and LiCoO2 as precursors. XRD and EDS were used to study the structure properties of the modified LiMn2O4. The electrochemical properties of the modified LiMn2O4 were also investigated. The results show that Li and Co atoms could insert into the LiMn2O4crystal lattice and a newly formed spinel phase, modified LiMn2O4 was obtained. The modified LiMn2O4 exhibits excellent cycle ability at room and elevated temperatures compared to pure LiMn2O4. The improved electrochemical stability of the modified LiMn2O4 attributes to the entrance of Li and Co ions inserted into the spinel crystal structure.
文摘Modified lithium manganese oxides were prepared by using LiMn 2 O 4 and LiCoO 2 as precursors by solid state reaction.A study has been carried out by TG - DSC,XRD and FTIR to analyze the reaction process and structural characterization of products.The results showed that the LiMn 2 O 4 reacted chemically with LiCoO 2 at high temper - ature.Li and Co atom could insert into the LiMn 2 O 4 crystal lattice and obtained the Cobalt - Doped spinel com - pound.The results of constant - current cyclic test showed that the cyclic stability of the products are increased with the amount of doped LiCoO 2 ,while their initial capacity is decreased.
基金Project(2002AA331010) supported by the Hi-tech Research and Development Program of China Project(BJ2000030) supported by the Natural Science Foundation of Jiangsu Province, China
文摘The ultra-high molecular mass polyethylene (UHMMPE) as an artificial joint acetabular material was filled with nano-powder of Al2O3 of various mass fractions. The effect of Al2O3 mass fraction on the hardness, wetting property and tribological properties of the Al2O3-UHMMPE composites under dry friction sliding against both stainless steel and Ti-6Al-4V alloy was investigated. The morphologies of the worn surfaces of composites were observed with optical microscope. The results show that, wetting property and wear resistance of the composites are improved by filling Al2O3, while the friction coefficient is decreased largely under dry friction as compared with that of the unfilled UHMMPE. This is attributed to the reinforcing function of the nano-powder of Al2O3 in the composites. The wear of UHMMPE is dominated by plowing, plastic deformation and fatigue wear; while the Al2O3-UHMMPE composites are characterized by the mild fatigue wear.
文摘通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后复合材料的带隙减小,光生载流子复合率大幅下降,当Bi_(2)S_(3)循环5次时,TiO_(2)纳米复合材料的光电化学性能最好。带隙减小到2.9 e V,光电流密度由改性前的200μA·cm^(-2)提升至550μA·cm^(-2),是改性前的2.75倍;将其与304不锈钢耦合后,电位降至-1.0 V,比改性前的耦合电位低80 m V,可以进一步提升对304不锈钢的光生阴极保护效果。
