By using a simply liquid phase method at a low temperature, rutile TiO 2 nanowhiskers were successfully prepared from TiCl 4 aqueous solution at 70 ℃ after aging for 11 d. The obtained TiO 2 nanowhiskers were charact...By using a simply liquid phase method at a low temperature, rutile TiO 2 nanowhiskers were successfully prepared from TiCl 4 aqueous solution at 70 ℃ after aging for 11 d. The obtained TiO 2 nanowhiskers were characterized by means of TEM,HRTEM and XRD. The results show that the nanowhiskers are rutile crystals growing along c-axis direction with a length of 100150 nm and a diameter 68 nm. The simple fabrication method of TiO 2 nanowhiskers will promote practical application of 1D TiO 2.展开更多
Dispersed cuprite （Cu2O） nanowhiskers were synthesized in a water/butanol/cyclohexane/cetyl trimethyl ammonium bromide （CTAB） water-in-oil microemulsion system at 25℃. The nanowhiskers with a diameter of about 8 ...Dispersed cuprite （Cu2O） nanowhiskers were synthesized in a water/butanol/cyclohexane/cetyl trimethyl ammonium bromide （CTAB） water-in-oil microemulsion system at 25℃. The nanowhiskers with a diameter of about 8 am exhibit a well-crystallized one-dimensional （1D） structure over several hundreds nanometers in length and mainly grow along the 〈111〉 direction. However, without CTAB, only cubic and hexagonal bulks are obtained. Without emulsifier, short and thick nanowhiskers can be prepared but they are apt to agglomerate. The possible growth mechanism of Cu2O nanowhiskers is speculated. The surfactant and the microemulsion system are related to the 1D shape formation and the even dispersion of Cu2O nanomaterials, respectively.展开更多
Mullite nanowhiskers with Al-rich structure were prepared by molten salt synthesis at 1000°C for 3 h in air using silica, amorphous silica, and ultrafine silica as the silica sources. The phase and morphology of ...Mullite nanowhiskers with Al-rich structure were prepared by molten salt synthesis at 1000°C for 3 h in air using silica, amorphous silica, and ultrafine silica as the silica sources. The phase and morphology of the synthesized products were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. A thermogravimetric and differential thermal analysis was carried out to determine the reaction mechanism. The results reveal that the silica sources play an important role in determining the morphology of the obtained mullite nanowhiskers. Clusters and disordered arrangements are obtained using common silica and amorphous silica, respectively, whereas the use of ultrafine silica leads to highly ordered mullite nanowhiskers that are 80-120 nm in diameter and 20-30 μm in length. Considering the growth mechanisms, mullite nanowhiskers in the forms of clusters and highly ordered arrangements can be attributed to heterogeneous nucleation, whereas disordered mullite nanowhiskers are obtained by homogenous nucleation.展开更多
A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that t...A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that the as-obtained samples have a monoclinic structure, and the whisker-MoO2 is composed of nanowires with diameters of ca. 20 nm. Formation of whisker-MoO2 was through a typical precursor-reduction process, in which cetyltrimethylammonium bromide （CTAB） served as a cationic surfactant and acetone as a reductant. The electrochemical behavior of whisker-MoO2 was studied.展开更多
ZnO nanopowders were prepared by oxidizing Zn vapor in the atmosphere of mixture gas of At and O2 at low pressure. Tetrapod nanowhiskers synthesized at a pressure of 1.6 kPa show pure ZnO feet and Zn phase in the core...ZnO nanopowders were prepared by oxidizing Zn vapor in the atmosphere of mixture gas of At and O2 at low pressure. Tetrapod nanowhiskers synthesized at a pressure of 1.6 kPa show pure ZnO feet and Zn phase in the core of the nanopowder. The ellipsoid ZnO nanoparticles were produced at the pressure of 10 kPa. The photodegradation rate of aniline and chemical oxygen demand removal demonstrate that the photocatalytic efficiency of Zn/ZnO nanowhiskers with UV irradiation is higher than that ofZnO nanoparticles. The tetrapod morphology and Zn phase inside nanowhiskers play key a role in photodegradation process.展开更多
The Mechanical properties of the hexagonal tungsten nanowhiskers, which were synthesized by chemical vapor deposition, were characterized by instrumented nanoindentation and atomic force microscope （AFM）. The nanoin...The Mechanical properties of the hexagonal tungsten nanowhiskers, which were synthesized by chemical vapor deposition, were characterized by instrumented nanoindentation and atomic force microscope （AFM）. The nanoindentation results show that tungsten nanowhiskers exhibit a hardness of （6.2±1.7） GPa and an elastic modulus of （225±20） GPa. According to the comparative test results, the tungsten nanowhiskers possess a comparable hardness to tungsten microwhiskers, and an hardness increase of 35% to the bulk single-crystal tungsten. The increase in the hardness of whiskers is attributed to the lacking of dislocation avalanche observed in the bulk single-crystal tungsten. The measured modulus is about 80% that of the tungsten microwhiskers, which can be contributed to the size effects of the nanowhiskers and the substrate effects in the nanoindentation test.展开更多
Due to their excellent dielectric properties and the rapid response to microwave irradiation,silicon carbide nanowhiskers(SiCNWs)were employed as microwave susceptor in this study to absorb microwave and locally melt ...Due to their excellent dielectric properties and the rapid response to microwave irradiation,silicon carbide nanowhiskers(SiCNWs)were employed as microwave susceptor in this study to absorb microwave and locally melt the surrounding polypropylene(PP)substrates for the joining of PP substrates.Complete welded joint is formed after the melted PP was cooled and resolidified.Other than microwave susceptor,SiCNWs also acted as the nanofillers in strengthening the welded joint through the formation of SiCNWs reinforced PP nanocomposite at the interface of PP substrates.Besides,the effect of microwave power on the microwave welding of PP substrates using SiCNWs as susceptor was studied and reported.It was found that the tensile strength and modulus of elasticity of the welded joint improved as microwave power increased.However,it deteriorates the flexibility of the welded joint as high stiffness SiCNWs were incorporated deeper into the PP matrix which restricted the PP chain mobility.Aside from microwave power,clamping pressure is also critical in determining the mechanical properties of a welded joint.When compared to unclamped welded joint,the tensile strength,modulus of elasticity and flexibility of welded joint subjected to clamping pressure improved drastically.Moreover,the tensile strength of welded joint increased when the clamping pressure was increased from P1 to P3,but decreased when the clamping pressure was further increased to P4 due to the occurrence of flashing at welded joint.The formation mechanism of SiCNWs reinforced PP welded joint was also proposed in this study.Compared to conventional welding,this welding process is easy,straightforward and is able to produce welded joint with outstanding mechanical properties via precise controlling of the processing parameters.Thus,microwave welding is thought to offer an option for the joining of thermoplastics and other applications.展开更多
文摘By using a simply liquid phase method at a low temperature, rutile TiO 2 nanowhiskers were successfully prepared from TiCl 4 aqueous solution at 70 ℃ after aging for 11 d. The obtained TiO 2 nanowhiskers were characterized by means of TEM,HRTEM and XRD. The results show that the nanowhiskers are rutile crystals growing along c-axis direction with a length of 100150 nm and a diameter 68 nm. The simple fabrication method of TiO 2 nanowhiskers will promote practical application of 1D TiO 2.
基金This work was financially supported by the National Natural Science Foundation of China (No. 20207002).
文摘Dispersed cuprite （Cu2O） nanowhiskers were synthesized in a water/butanol/cyclohexane/cetyl trimethyl ammonium bromide （CTAB） water-in-oil microemulsion system at 25℃. The nanowhiskers with a diameter of about 8 am exhibit a well-crystallized one-dimensional （1D） structure over several hundreds nanometers in length and mainly grow along the 〈111〉 direction. However, without CTAB, only cubic and hexagonal bulks are obtained. Without emulsifier, short and thick nanowhiskers can be prepared but they are apt to agglomerate. The possible growth mechanism of Cu2O nanowhiskers is speculated. The surfactant and the microemulsion system are related to the 1D shape formation and the even dispersion of Cu2O nanomaterials, respectively.
基金the New Century Excellent Talents in Universities (No. NECT-12-0779)the Fundamental Research Funds for the Central Universities (No. FRF-SD-13-006A)the Program for Changjiang Scholars and Innovative Research Team in Universities (No. IRT1207) for financial support
文摘Mullite nanowhiskers with Al-rich structure were prepared by molten salt synthesis at 1000°C for 3 h in air using silica, amorphous silica, and ultrafine silica as the silica sources. The phase and morphology of the synthesized products were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. A thermogravimetric and differential thermal analysis was carried out to determine the reaction mechanism. The results reveal that the silica sources play an important role in determining the morphology of the obtained mullite nanowhiskers. Clusters and disordered arrangements are obtained using common silica and amorphous silica, respectively, whereas the use of ultrafine silica leads to highly ordered mullite nanowhiskers that are 80-120 nm in diameter and 20-30 μm in length. Considering the growth mechanisms, mullite nanowhiskers in the forms of clusters and highly ordered arrangements can be attributed to heterogeneous nucleation, whereas disordered mullite nanowhiskers are obtained by homogenous nucleation.
基金This work was financially supported by the National Natural Science Foundation of China （No.20271001）.
文摘A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that the as-obtained samples have a monoclinic structure, and the whisker-MoO2 is composed of nanowires with diameters of ca. 20 nm. Formation of whisker-MoO2 was through a typical precursor-reduction process, in which cetyltrimethylammonium bromide （CTAB） served as a cationic surfactant and acetone as a reductant. The electrochemical behavior of whisker-MoO2 was studied.
基金the National Natural Science Foundation of China(No:30571536)Junye Nano Materials Company Limited(Shenzhen,China)
文摘ZnO nanopowders were prepared by oxidizing Zn vapor in the atmosphere of mixture gas of At and O2 at low pressure. Tetrapod nanowhiskers synthesized at a pressure of 1.6 kPa show pure ZnO feet and Zn phase in the core of the nanopowder. The ellipsoid ZnO nanoparticles were produced at the pressure of 10 kPa. The photodegradation rate of aniline and chemical oxygen demand removal demonstrate that the photocatalytic efficiency of Zn/ZnO nanowhiskers with UV irradiation is higher than that ofZnO nanoparticles. The tetrapod morphology and Zn phase inside nanowhiskers play key a role in photodegradation process.
基金Projects(50804057,51074188) supported by the National Natural Science Foundation of ChinaProject(08C580) supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2012T50703,2011M500128) supported by China Postdoctoral Science Foundation Funded Project and Postdoctoral Science Foundation of Central South University,China
文摘The Mechanical properties of the hexagonal tungsten nanowhiskers, which were synthesized by chemical vapor deposition, were characterized by instrumented nanoindentation and atomic force microscope （AFM）. The nanoindentation results show that tungsten nanowhiskers exhibit a hardness of （6.2±1.7） GPa and an elastic modulus of （225±20） GPa. According to the comparative test results, the tungsten nanowhiskers possess a comparable hardness to tungsten microwhiskers, and an hardness increase of 35% to the bulk single-crystal tungsten. The increase in the hardness of whiskers is attributed to the lacking of dislocation avalanche observed in the bulk single-crystal tungsten. The measured modulus is about 80% that of the tungsten microwhiskers, which can be contributed to the size effects of the nanowhiskers and the substrate effects in the nanoindentation test.
基金financially supported by the Department of Education,Ministry of Education Malaysia(MOE)through Fundamental Research Grant Scheme(FRGS/1/2019/TK05/UNIMAP/02/7)[FRGS 9003-00729]。
文摘Due to their excellent dielectric properties and the rapid response to microwave irradiation,silicon carbide nanowhiskers(SiCNWs)were employed as microwave susceptor in this study to absorb microwave and locally melt the surrounding polypropylene(PP)substrates for the joining of PP substrates.Complete welded joint is formed after the melted PP was cooled and resolidified.Other than microwave susceptor,SiCNWs also acted as the nanofillers in strengthening the welded joint through the formation of SiCNWs reinforced PP nanocomposite at the interface of PP substrates.Besides,the effect of microwave power on the microwave welding of PP substrates using SiCNWs as susceptor was studied and reported.It was found that the tensile strength and modulus of elasticity of the welded joint improved as microwave power increased.However,it deteriorates the flexibility of the welded joint as high stiffness SiCNWs were incorporated deeper into the PP matrix which restricted the PP chain mobility.Aside from microwave power,clamping pressure is also critical in determining the mechanical properties of a welded joint.When compared to unclamped welded joint,the tensile strength,modulus of elasticity and flexibility of welded joint subjected to clamping pressure improved drastically.Moreover,the tensile strength of welded joint increased when the clamping pressure was increased from P1 to P3,but decreased when the clamping pressure was further increased to P4 due to the occurrence of flashing at welded joint.The formation mechanism of SiCNWs reinforced PP welded joint was also proposed in this study.Compared to conventional welding,this welding process is easy,straightforward and is able to produce welded joint with outstanding mechanical properties via precise controlling of the processing parameters.Thus,microwave welding is thought to offer an option for the joining of thermoplastics and other applications.
文摘文章采用常温酸化法,以氯化钙和浓硫酸为原料,乙醇-水为混合溶剂,十六烷基三甲基溴化铵(CTAB)为晶型控制剂,室温条件下大规模制备了纳米硫酸钙晶须。用X-射线衍射仪(X-ray diffraction,XRD)、场发射扫描电子显微镜(field emission scanning electron microscopy,FESEM)和高分辨透射电子显微镜(high resolution transmission electron microscopy,HRTEM)等对所制备的样品进行表征。实验结果表明:反应温度、氯化钙初始浓度、醇水比(体积比)及反应时间等合成条件的变化对CaSO_4·2H_2O晶须的形貌和尺寸有重要的影响;所确定的优化合成工艺为:反应温度25℃、氯化钙初始浓度0.045mol/L、醇水比2∶1、反应时间30min;在该优化条件下所制备的硫酸钙晶须尺寸均匀、直径约为200nm、长径比约为30。
