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61.
Halogen-functionalized graphenes are utilized as electronic devices and energy materials. In the present paper, the effects of halogen-termination of graphene edge on the structures and electronic states of graphene flakes have been investigated by means of density functional theory (DFT) method. It was found that the ionization potential (Ip) and electron affinity of graphene (EA) are blue-shifted by the halogen termination, while the excitation energy is red-shifted. The drastic change showed a possibility as electronic devices such as field-effect transistors. The change of electronic states caused by the halogen termination of graphene edge was discussed on the basis of the theoretical results. 相似文献
62.
Bikash KarmakarJulie Banerji 《Tetrahedron letters》2011,52(38):4957-4960
A simple, efficient, and eco-friendly method for the synthesis of 1-(α-aminoalkyl) naphthols, the Betti bases, has been carried out over a basic nanocrystalline MgO catalyst in aqueous condition. The method has been applied for the synthesis of a range of compounds with variable functionalities in excellent yield and selectivity. 相似文献
63.
K. Sadhana 《Journal of magnetism and magnetic materials》2010,322(23):3729-3736
The nanocrystalline Ni0.53Cu0.12Zn0.35Fe1.88O4 and BaTiO3 powders were prepared using Microwave-Hydrothermal (M-H) method at 160 °C/45 min. The as synthesized powders were characterized using the X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). The size of the powders that were synthesized using M-H system was found to be ∼30 and ∼50 nm for ferrite phase and ferroelectric phases, respectively. The powders were densified using microwave sintering method at 900 °C/30 min. The ferrite and ferroelectric phases were observed from XRD and morphology of the composites was observed with the Scanning Electron Microscope (SEM).The magnetic hysteresis loops were recorded using the Vibrating Sample Magnetometer (VSM).The frequency dependence of real (μ′) and imaginary (μ″) parts of permeability was measured in the range of 1 MHz-1.8 GHz. The permeability decreases with an increase of BaTiO3 content at 1 MHz. The transition temperature (TC) of ferrite was found to be 245 °C. The TC of composite materials decreases with an increase in BaTiO3 content. 相似文献
64.
M. Lakshmi Kantam Kalluri V.S. Ranganath Lakkoju Chakrapani 《Tetrahedron letters》2007,48(43):7646-7649
Highly enantioselective Michael addition of malonates to cyclic and acyclic enones has been achieved by using nanocrystalline magnesium oxide at −20 °C. 相似文献
65.
Biao Zhou Ya-Wen Zhang Chun-Sheng Liao Chun-Hua Yan Liang-Yao Chen Song-You Wang 《Journal of magnetism and magnetic materials》2004,280(2-3):327-333
A series of rare-earth (RE)-doped nanocrystalline CoFeMn0.9RE0.1O4 thin films were prepared on monocrystalline silicon substrate by a sol–gel process, and the influences of the various RE3+ ions on the microstructure, magnetism and polar magneto-optical Kerr effects of the as-deposited films were examined. The results revealed that both of the magnetism and Kerr effect of CoFeMn0.9RE0.1O4 films could be mediated by doping with various RE3+ ions. The trend of both MS and HC of CoFeMn0.9RE0.1O4 films is similar to that of Bohr magneton across the series of rare-earth ions. The position of Kerr rotation peaks was red-shifted and their intensities increased, especially when doping with La3+, Tb3+, Y3+ or Yb3+ and so on. The enhanced MOKEs in CoFeMn0.9RE0.1O4 nanocrystalline thin films might promise their applications for magneto-optical recording in the future. 相似文献
66.
S.N. Sharma S. Kohli A.C. Rastogi 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):554-561
Thin films of TiO2 with high volume fraction (40–55%) and crystallite size (6–40 nm) of CdTe nanoparticles had been prepared by rf magnetron sputtering from a composite TiO2:CdTe target at room temperature and 373 K. A detailed optical properties of nanocrystalline CdTe:TiO2 films as-deposited and after thermal treatment (300 °C) are studied. The absorbance of the TiO2 films with CdTe nanocrystallite dispersions depends both on the nanocrystallite size and volume fraction. The blue-shifts of the optical absorption edge concurrent with the CdTe nanocystal size reduction for as-deposited and after thermal treatment of nanocrystalline CdTe:TiO2 thin films with respect to the bulk semiconductor agrees quite well with the strong quantum confinement theory. A slight deviation in absorption edge values than the predicted values from the strong quantum confinement model can be attributed to change in interplanar distance due to oxygen incorporation and inhomogeneous size distribution of CdTe nanocrystallites in these films. 相似文献
67.
Osamu Kido Mami Kurumada Katsuya Kamitsuji Toshiaki Tanigaki Takeshi Sato Yuki Kimura Hitoshi Suzuki Yoshio Saito Chihiro Kaito 《Physica E: Low-dimensional Systems and Nanostructures》2006,31(2):169-173
The synthesis of Al–Cr single quasicrystal (QC) nanoparticles of the decagonal phase was achieved by introducing an advanced gas flow evaporation method. By obtaining successive electron diffraction patterns for single-QC nanoparticles, the phase transformation temperature of a single-QC nanoparticle was determined to be 700 °C. It was also determined that part of the QC nanoparticle decomposed into hex-Al8Cr5 and Al during the phase transformation. Since the grain growth did not occur during the phase transformation in the present experiment, the inherent phase transformation temperature could be measured. 相似文献
68.
Discussed in this review are various solution-phase methodologies and specific chemical reactions involving molecular precursors and/or species derived there-from which have been utilized to synthesize various binary and ternary nanocrystalline III-V (13–15) compound semiconductors. 相似文献
69.
本文提出了一种填补国内空白的新产品-气体分析用锡片和锡囊的研制方法。对锡片,锡囊的外观和内在质量检测结果证明,研制的锡片,锡囊完全达到了美国LECO公司同类产吕的技术标准,而价格只有进口产品的四分之一左右。应用结果表明,该产品完全可以取代进口,完全适用于用事种金属及其俣金材料中气体分析的要求。 相似文献
70.
Nanocrystalline diamond (NCD) films were grown on silicon substrates by hot filament chemical vapor deposition in Ar/N2/CH4 gas mixtures. The effects of seeding process prior to deposition, the total gas pressure, and concentration of nitrogen on the grain size, morphology and bonding nature in HFCVD technique were investigated. The results indicated that a low total gas pressure is favorable for nanosized diamond crystallites. Films micrograph obtained from scanning electron microscopy showed diamond nanograins elongated with the addition of nitrogen in the plasma. Crystal structure investigations were carried out by X-ray diffraction measurements for deposited films. An increase in the size of crystallite is also observed from XRD measurements in NCD film when nitrogen was added in plasma. From Raman spectra, it was observed that the relative intensity of G peak increases indicating more graphite content after nitrogen added in the plasma. The effects of the nitrogen incorporation in nanocrystalline films in HFCVD are discussed. 相似文献