Xiang QI
,
Jun ZHANG
材料科学技术（英）
The substrate pre-treatment plays a key role in obtaining hollow-cored carbon nanotubes (CNTs) and solidcored carbon nanofibers (CNFs) from flames. This paper introduces a simply and high-efficient process by coating a NiSO4 or FeSO4 layer on the substrate as catalyst precursors. Comparing with the regular pretreatment methods, the present experiments showed that the coating pre-treatment provided the following advantages: 1) greatly shortening the synthesis time; 2) available variant substrates and carbon sources; 3) narrowing the diameters distribution. The sulfate is considered to be a crucial factor at the growth of CNTs and CNFs, because it increases the surface energy of catalyst particles and the surface specificity of sulfurs action in metallic grains. This novel process provides a possibility for high quality and mass production of CNTs and CNFs from flames.
关键词:
Carbon nanotubes
,
nanotubes
,
carbon
,
nanofibers
,
flam
周谦莉
,
杜挺
金属学报
利用下列组装的固体电解质定氧电池Mo/Cr,Cr_2O_3//ZrO_2(MgO)//[O],Ce_2O_2S/Mo+ZrO_2金属陶瓷,Mo.在1600℃温度下对含微量C的Fe-Nb-Ce溶液进行热力学性质的研究。实验测得1600℃时Fe液中反应Ce_2O_2S=2[Ce]+2[O]+[S]的平衡常数和Ce_2O_2S的标准生成自由能分别为K=4.395×10~(-15),ΔG°_(Ce_2O_2S)=-514.786kJ·mol~(-1);Ce与Nb的活度相互作用系数为e_(Nb)~(Ce)=-2.306,e_(Ce)~(Nb)=-3.481。 随着Nb含量的增加,在微量碳含量的条件下,产物中存在NbC化合物,本文对NbC的生成问题进行了探讨,并得到1600℃时,Fe液中NbC的标准生成自由能为ΔG°_(NbC)=-87.111kJ·mol~(-1)。
关键词:
Fe-Nb-Ce溶液
,
thermodynamic properties
,
oxygen
,
sulphur
,
carbon
武蕴忠
,
丁青
,
徐梅芳
,
王渭源
金属学报
用Ａｕｇｅｒ电子能谱研究铂薄膜中氧和碳杂质的行为．结果表明，氧和碳受它们在铂膜中扩散过程限制．在１０００℃上、下两个温区，氧具有不同的扩散激活能，分别等于０．９８和０．４４ｅＶ；５５０─１０００℃温度范围内，氧向膜外扩散，使铂膜净化；１０００─１２００℃温度范围内，氧向膜内扩散，使铂膜氧化．在所研究的整个温度范围内，碳的扩散激活能等于０．５２ｅｖ，其扩散行为和氧相同，且随着氧含量的增减而增减．
关键词:
Ａｕｇｅｒ电子能谱
,
Pt film
,
oxygen
,
carbon
,
null
Xiuyun SUN
,
Yugang SUN
材料科学技术（英）
This article reviews the use of electronic quality single-walled carbon nanotubes grown via chemical vapor deposition (CVD) approaches at high temperatures as building blocks for fabricating flexible field-effect devices, such as thin-film transistors (TFTs) and chemical sensors. Dry transfer printing technique is developed for forming films of CVD nanotubes on low-temperature plastic substrates. Examples of TFTs with the use of nanotubes and thin dielectrics and hydrogen sensors with the use of nanotubes decorated with palladium nanoparticles are discussed in detail to demonstrate the promising potentiality of single-walled carbon nanotubes for building high performance flexible devices, which can find applications where traditional devices on rigid substrates are not suitable.
关键词:
Single-walled carbon nanotubes
,
carbon
,
nanotubes
,
flexible
JunhHua WU
材料科学技术（英）
Microwave dielectric measurements over the broad bandwith of 10 MHz to 20 GHz were conducted on composites comprising bundles of single-walled carbon nanotubes (SWNT) embedded in an epoxy matrix, in comparison to the nano-graphite and MWNT. It is found that both relative real and imaginary permittivity of the nanocomposites are strong functions of the SWNT concentration, showing large, wide dielectric and electrical response. Distinct resonance around 1.5 GHz is observed at high SWNT concentrations, accompanied by the downshift of the resonance frequency with increasing concentration. Largely, the SWNT-epoxy composites share the behavior of the MWNT owing to structural similarity, much more effective than the nano-graphite. The remarkable, broadband dielectric and electrical properties of the nanotubes acquired in the work originate from their unique seamless graphene architectures, modeled by two major contributions, dielectric relaxation/resonance and electronic conduction, which is substantiated by the agreement between theoretical analysis and experimental results. The carbon nanotube composites are prospective for microwave applications and offer experimental evidence for fundamental studies in low-dimensional systems.
关键词:
Single-walled carbon nanotube
,
carbon
,
nanotube
,
Dielectric
Y.Sakamoto
金属学报(英文版)
For the aim of synthesis of the carbon-iodine compound, the preparation of iodine-included carbon using RF plasma CVD was studied. Iodine-included carbon was synthesized on Si substrate using ICP type RF plasma CVD apparatus. C2H5OH and I2 dissolved C2H5OH was used as reactant gases. As a result, surface morphologies of Iodine included carbon films showed flat surfaces for each samples. On the structure of films estimated by Raman spectroscopy, amorphous carbon was recognized. And I2 peaks were observed in XPS spectra. As a result of friction test, friction coefficient of the sample growth with C2H5OH showed about 0.45. On the other hand, that of the sample with I2-C2H5OH showed about 0.3 and decrease of friction coefficient was recognized. Iodine inclusion for carbon materials can be achieved by RF plasma CVD using an I2-C2H5OH reactant. The coefficient of iodine-included carbon showed lower than of without iodine.
关键词:
carbon
,
null
,
null
,
null
Huayu ZHANG
,
Liangxue LIU
,
Yulei WANG
材料科学技术（英）
Nitrogen doped diamond-like carbon (DLC:N) films were prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) on polycrystalline Si chips. Film thickness is about 50 nm. Auger electron spectroscopy (AES) was used to evaluate nitrogen content, and increasing N2 flow improved N content from 0 to 7.6%. Raman and X-ray photoelectron spectroscopy (XPS) analysis results reveal N-sp3C and N-sp2C structure. With increasing the N2 flow, sp3C decreases from 73.74% down to 42.66%, and so does N-sp3C from 68.04% down to 20.23%. The hardness decreases from 29.18 GPa down to 19.74 GPa, and the Young′s modulus from 193.03 GPa down to 144.52 GPa.
关键词:
Nitrogen doped diamond-like carbon films
,
doped
,
diamond-like
,
carbon
,
films
J.Koh
,
B.Kim
材料科学技术（英）
We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomole-cular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) or “surface programmed assembly” method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.
关键词:
Chemical vapour deposition
,
vapour
,
deposition
,
carbon
,
nanotu
