The stability of open edged multi-walled carbon nanotubes has been investigated by using in situ high resolution transmission electron microscopy at elevated temperatures.Formation of inter-shell structures was experi...The stability of open edged multi-walled carbon nanotubes has been investigated by using in situ high resolution transmission electron microscopy at elevated temperatures.Formation of inter-shell structures was experimentally observed for the first time and attributed to a robust interaction between adjacent concentric shells(so-called lip lip interaction).The fl uctuating behavior of the inter-shell structures suggests a mechanism by which the carbon atoms can pass in or out through the inter-shell edges during carbon nanotube growth or shrinkage processes.展开更多
Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(...Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(ErCl_(3)@SWCNTs)characterized.Encapsulation under high temperature and vacuum using high quality SWCNTs results in a high fi lling-ratio of ErCl_(3) nanowires in the SWCNTs.The high fi lling-ratio of ErCl_(3) nanowires and the use of highly pure SWCNTs with only a small amount of residual Fe catalyst nanoparticles enabled us to observe the magnetic properties of ErCl_(3)@SWCNTs.Structure determination based on simulated annealing calculations and high-resolution transmission electron microscope(HRTEM)image simulations revealed that the structure of the ErCl_(3) nanowires is unusual with respect to the coordination environment of the Eu3+ions.This work opens up new possibilities to fabricate various metal complex nanowires with high yield and may also be of more general importance in understanding and exploring magnetic properties in low-dimensional magnetic systems.展开更多
The development is described of an electromechanical bimorph actuator composed of ionic liquid gel sandwiched by electrochemically treated millimeter-long single-walled carbon nanotubes(SG-SWNT).Electrochemical doping...The development is described of an electromechanical bimorph actuator composed of ionic liquid gel sandwiched by electrochemically treated millimeter-long single-walled carbon nanotubes(SG-SWNT).Electrochemical doping of the SG-SWNT and electrochemical polymerization of polypyrrole on the surface of the SG-SWNT improved the performance of a previously reported actuator using non-treated SG-SWNTs.The conductivity of the SG-SWNT sheets treated at the anodic potential(doped)was found to be three times larger than that of the original film.The generated strain of the actuator prepared from the doped SG-SWNT sheets was increased compared to that prepared from non-doped sample.Moreover,the generated strain of the actuator from the doped SG-SWNT sheets swelled with ionic liquid(IL)was increased to twice that without ILs.The electropolymerization of pyrrole on the surface of the SG-SWNT sheet was carried out.The conductivity of the SG-SWNT was seven times larger after the electropolymerization.The generated strain of the SG-SWNT actuator prepared from the SG-SWNT sheets with electropolymerization was twice as large as that without the electropolymerization at low frequency.At higher frequency,both actuators provide almost the same performance.Both actuators exhibit mechanical resonance at about 100 Hz.展开更多
Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, us...Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, usually exhibit reversible host rearrangement between P-type and O-type stacking upon charge/discharge. Herein we demonstrate that such host rearrangement is unfavorable and can be suppressed by introducing transition-metal ions into sodium layers. The electrode with stabilized P3-type stacking delivers superior rate capability, high energy efficiency, and excellent cycling performance. Owing to the cation-mixing nature, it performs the lowest lattice strain among all reported cathodes for sodium-ion batteries. Our findings highlight the significance of a stable host for sodium-ion storage and moreover underline the fundamental distinction in material design strategy between lithium-and sodium-ion batteries.展开更多
基金The work on microscopy is partly supported by CREST and KAKENHI(19054017).
文摘The stability of open edged multi-walled carbon nanotubes has been investigated by using in situ high resolution transmission electron microscopy at elevated temperatures.Formation of inter-shell structures was experimentally observed for the first time and attributed to a robust interaction between adjacent concentric shells(so-called lip lip interaction).The fl uctuating behavior of the inter-shell structures suggests a mechanism by which the carbon atoms can pass in or out through the inter-shell edges during carbon nanotube growth or shrinkage processes.
基金by the JST CREST Program for novel carbon nanotube materialsThe XAS experiments were performed at BL25SU in SPring-8 with the approval of JASRT(Proposal No.2007B1732).
文摘Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(ErCl_(3)@SWCNTs)characterized.Encapsulation under high temperature and vacuum using high quality SWCNTs results in a high fi lling-ratio of ErCl_(3) nanowires in the SWCNTs.The high fi lling-ratio of ErCl_(3) nanowires and the use of highly pure SWCNTs with only a small amount of residual Fe catalyst nanoparticles enabled us to observe the magnetic properties of ErCl_(3)@SWCNTs.Structure determination based on simulated annealing calculations and high-resolution transmission electron microscope(HRTEM)image simulations revealed that the structure of the ErCl_(3) nanowires is unusual with respect to the coordination environment of the Eu3+ions.This work opens up new possibilities to fabricate various metal complex nanowires with high yield and may also be of more general importance in understanding and exploring magnetic properties in low-dimensional magnetic systems.
文摘The development is described of an electromechanical bimorph actuator composed of ionic liquid gel sandwiched by electrochemically treated millimeter-long single-walled carbon nanotubes(SG-SWNT).Electrochemical doping of the SG-SWNT and electrochemical polymerization of polypyrrole on the surface of the SG-SWNT improved the performance of a previously reported actuator using non-treated SG-SWNTs.The conductivity of the SG-SWNT sheets treated at the anodic potential(doped)was found to be three times larger than that of the original film.The generated strain of the actuator prepared from the doped SG-SWNT sheets was increased compared to that prepared from non-doped sample.Moreover,the generated strain of the actuator from the doped SG-SWNT sheets swelled with ionic liquid(IL)was increased to twice that without ILs.The electropolymerization of pyrrole on the surface of the SG-SWNT sheet was carried out.The conductivity of the SG-SWNT was seven times larger after the electropolymerization.The generated strain of the SG-SWNT actuator prepared from the SG-SWNT sheets with electropolymerization was twice as large as that without the electropolymerization at low frequency.At higher frequency,both actuators provide almost the same performance.Both actuators exhibit mechanical resonance at about 100 Hz.
基金The financial support from the National Basic Research Program of China(2014CB932300)Natural Science Foundation of Jiangsu Province of China(BK20170630)+1 种基金NSF of China(21633003 and 51602144)sponsored by the JST-CREST ‘‘Phase Interface Science for Highly Efficient Energy Utilization",JST(Japan)
文摘Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, usually exhibit reversible host rearrangement between P-type and O-type stacking upon charge/discharge. Herein we demonstrate that such host rearrangement is unfavorable and can be suppressed by introducing transition-metal ions into sodium layers. The electrode with stabilized P3-type stacking delivers superior rate capability, high energy efficiency, and excellent cycling performance. Owing to the cation-mixing nature, it performs the lowest lattice strain among all reported cathodes for sodium-ion batteries. Our findings highlight the significance of a stable host for sodium-ion storage and moreover underline the fundamental distinction in material design strategy between lithium-and sodium-ion batteries.
