Showing papers in "International Journal of Nanoscience in 2009"
TL;DR: The morphology, crystal structure and thermal properties of silver palmitate were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and Thermogravimetry as mentioned in this paper.
Abstract: In order to supply high quality silver source to photothermographic material based on silver carboxylate, silver plamitate was prepared by chemical deposition method using palmitic acid, sodium hydroxide, silver nitrate as raw materials and PVP as surfactant in water system. The morphology, crystal structure and thermal properties of silver palmitate were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and Thermogravimetry (TG). The results indicate that silver palmitate has good purity and well-defined layer structure with triclinic phase. The diameter of fiber-like silver palmitate is about 200 nm, which shows excellent dispersion properties. DSC curves demonstrate that silver palmitate has seven endothermic peaks below 240°C. Five endothermic peaks below 190°C assign to different phase transitions. Silver palmitate decomposed step-by-step at 204.1, 223.6, and 253.9°C.
16 citations
TL;DR: In this paper, the effect of ligand exchange on the optical and photoluminescence properties of Au25SG18 (SG-glutathione thiolate) clusters was investigated.
Abstract: Effect of ligand exchange on the optical and photoluminescence properties of Au25SG18 (SG-glutathione thiolate) clusters was investigated. A fluorescein-based dye, 5-((2-(and-3)-S-(acetylmercapto)succinoyl)amino)-fluorescein (SAMSA) was anchored on water soluble Au25SG18 clusters by the place exchange reaction and the solid-state emission of the exchange product was studied. Inherent fluorescence image of these clusters was mapped. Organic soluble Au25(SC2H4Ph18 clusters were synthesized as a model system which also showed temperature-dependent solid-state emission, in good agreement with the results from water soluble Au25 clusters.
15 citations
TL;DR: In this article, the authors considered the need for high-capacity capacitors of micron size to meet the challenge of deep-subvoltage nanoelectronics and related technologies, and the necessity of developing all-solid-state impulse micron-sized supercapacitors on the basis of advanced superionic conductors.
Abstract: The decrease of energy consumption per 1 bit processing (e) and power supply voltage (Vdd) of integrated circuits (ICs) are long-term tendencies in micro- and nanoelectronics. In this framework, deep-sub-voltage nanoelectronics (DSVN), i.e., ICs of ~1011–1012 cm-2 component densities operating near the theoretical limit of e, is sure to find application in the next 10 years. In nanoelectronics, the demand on high-capacity capacitors of micron sizes sharply increases with a decrease of technological norms, e and Vdd. Creation of high-capacity capacitors of micron size to meet the challenge of DSVN and related technologies is considered. The necessity of developing all-solid-state impulse micron-sized supercapacitors on the basis of advanced superionic conductors (nanoionic supercapacitors) is discussed. Theoretical estimates and experimental data on prototype nanoionic supercapacitors with capacity density δC ≈ 100 μF/cm2 are presented. Future perspectives of nanoionic devices are briefly discussed.
13 citations
TL;DR: In this article, polycaprolactone-polylactide block copolymers (PCL-block-PLA) were grafted onto filled multi-wall carbon nanotubes (MWCNT) successfully.
Abstract: Polycaprolactone-polylactide block copolymers (PCL-block-PLA) were grafted onto filled multi-wall carbon nanotubes (MWCNT) successfully. In this synthesis, MWCNTs were opened and functionalized, and then they were filled by silver nanoparticles. The filled MWCNT were used as macroinitiator for ring opening polymerization of e-caprolactone and L-lactide. Then the end hydroxyl functional groups of MWCNT-graft-PCL or MWCNT-graft-PLA were used as initiator for ring opening polymerization of lactide and e-caprolactone and MWCNT-graft-PCL-block-PLA or MWCNT-graft-PLA-block-PCL were obtained, respectively. Length of grafted copolymer chains onto the MWCNT was controlled using CNT/monomer ratio. Nanocomposites' properties depend on the length of polymer blocks strongly. Structure of nanocomposites was evaluated by TEM and spectroscopy methods.
12 citations
TL;DR: In this article, different additives such as cetyltrimethylammonium bromide (CTAB), aluminum nitrate and tri-n-octylphosphine oxide (TOPO) are selected, respectively, to bind zinc acetate in order to investigate its role in the formation of ZnO nanoparticles.
Abstract: In this study, different additives such as cetyltrimethylammonium bromide (CTAB), aluminum nitrate and tri-n-octylphosphine oxide (TOPO) are selected, respectively, to bind zinc acetate in order to investigate its role in the formation of ZnO nanoparticles Accordingly, the morphology and size of produced ZnO nanoparticles are affected by existence of the additives through XRD analyses and TEM observations The particle size was found to be 32, 14, 15, and 28 nm for pure zinc acetate, zinc acetate/TOPO, zinc acetate/CTAB, and zinc acetate/aluminum nitrate, respectively It is observed that the TOPO and CTAB decrease the size of ZnO nanoparticles, while the doping of aluminum to the precursor has no effect on its particle size The obtained ZnO nanoparticles exhibited the direct optical bandgap of about 340–345 eV and their photoluminescence spectrum has a UV emission peak at about 363 nm which is slightly blue-shifted due to the smaller particle size of the ZnO nanoparticles in the presence of TOPO and CTAB additives
11 citations
TL;DR: The pH value of the HSA solution prior to the desolvation procedure was identified as the major factor determining particle size and the amount of crosslinker showed that it has less effect on produced nanoparticle size.
Abstract: Human Serum Albumin (HSA) nanoparticles represent promising drug carrier systems. Particle size is a crucial parameter in particular for the in vivo behavior of nanoparticles after intravenous injection. The object of present study was to characterize the desolvation process of HSA for preparation of nanoparticles. Two process parameters were examined to achieve a suitable size of nanoparticles such as the pH value and the amount of glutaraldehyde concentration (%). The smallest size of nanoparticles achieved was 91 nm and the largest size was 388 nm which is suitable for drug delivery. The pH value of the HSA solution prior to the desolvation procedure was identified as the major factor determining particle size and the amount of crosslinker showed that it has less effect on produced nanoparticle size. The nanoparticle sample was purified by five cycles' centrifugation (20 000× g, 8 min) and redispersion of the pellet to the original volume in 10 mM NaCl at pH values of 7.5–9, respectively, and then analyzed by particle size analyzer (PCS).
11 citations
TL;DR: In this article, temperature variant EPR has been performed in order to study the relaxation mechanism in zinc ferrite nanoparticles, and the particle size of the samples were measured by the X-ray diffraction and Transmission Electron Microscopy.
Abstract: The electron paramagnetic resonance (EPR) is a well known tool to investigate the magnetic relaxation phenomena in the magnetic particles. For the present investigation, temperature variant EPR has been performed in order to study the relaxation mechanism in zinc ferrite nanoparticles. The magnetic nanoparticles were synthesized by using the nitrates of zinc and iron, and citric acid. The particle size of the samples were measured by the X-ray diffraction and Transmission Electron Microscopy. A more precise, Williamson–Hall (W–H) approach was used for the determination of the particle size as well as the strain in nanoparticles. The kinematics of magnetic moment has been studied with the help of temperature dependent EPR spectroscopy. Relaxation time calculations and temperature dependence of linewidth show the dominance of spin-lattice relaxation in these systems. Both nanoparticle systems show the presence of direct and Raman process in the relaxation mechanism and completely rule out the presence of Orbach process.
10 citations
TL;DR: In this article, the magnetopolaron state in a cylindrical quantum dot with a transverse parabolic potential and a high rectangular potential well in the longitudinal direction was examined.
Abstract: We examine the magnetopolaron state in a cylindrical quantum dot with a transverse parabolic potential and a high rectangular potential well in the longitudinal direction. The quadratic dependence of the magnetopolaron energy versus Frohlich electron–phonon coupling constant for different cyclotron radii and constant structure radius is modulated by a logarithmic function seems to depend on the Frohlich coupling constant. The same law is seen in the case of magnetopolaron energy versus Frohlich electron–phonon coupling constant for different structure radii and constant cyclotron radius. The energies are seen to be lifted in different fashions in the case of the structure and cyclotron radii. The high degrees of confinement (or high magnetic field) lead to an enhancement in the effective electron–phonon coupling that in turn brings about the possibility that in spite of weak polar coupling as in GaAS say, the polaron problem may also have strong-coupling counterparts arising from confinement or magnetic field effects. The polaron mass increases with increasing Frohlich electron–phonon coupling constant. The dependence seems to be fourth-order law of the Frohlich coupling constant modulated by a logarithmic function.
9 citations
TL;DR: In this article, a novel gap fill material has been optimized and developed for global planarization properties in advanced lithographic and nano-imprinting techniques, which can provide dry etching selectivity to the under-layer to avoid damaging the dielectric materials.
Abstract: This study focuses on the correlation between simulation and experiment using UV curable gap fill materials for global planarization in advanced lithographic and nanoimprinting techniques. A novel gap fill material has been optimized and developed for global planarization properties. Gap fill materials planarize irregular substrates such as patterned steps, vias, and trenches to increase depth of focus and patterning resolution. After planarizing the substrate surface, the gap fill materials provide dry etching selectivity to the under-layer to avoid damaging the dielectric materials. In the characterization of UV curable gap fill materials, two key factors were identified. The factors were the specific dependence of planarization on the spin speed and film thickness. By optimizing these factors, an appreciable reduction in via topography was realized. An array of 1.1 μm deep, 300 nm diameter holes was planarized to 10 nm thickness bias with a 380 nm thick planarizing film. In addition of global planarization, a final design consideration was to reduce the amount of outgassing during the process. UV curable gap fill material was optimized for sublimate reduction resulting in a defect-free coating. The sublimate produced from the developed gap fill material during baking was significantly decreased when compared with that produced from a thermal curable material. And, the third evaluation of UV curable gap fill materials was reported, to avoid resist poisoning issues in an advanced via-first dual damascene process. The resist poisoning properties in UV curable gap fill material were observed better performance than that of thermal curable material. The resulting UV curable gap fill materials based on this study will be extremely useful for lithographic and nanoimprinting techniques.
8 citations
TL;DR: In this paper, the effect of voltage type (AC/DC), time delay in turning off the voltage, tungsten wire diameter, environmental vibrations, electrolyte type, cathode material, and perpendicularity of tengsten wire (toward electrolyte surface) on the tip sharpness are investigated.
Abstract: With developments in nanoscience and nanotechnology, Scanning Tunneling Microscope (STM) has found a wide application in imaging the atoms, molecules, and nanostructures. This microscope uses an ultra sharp metallic tip for scanning sample surface to produce surface topographic image with atomic resolution. Reliability and resolution of STM images depend largely on the sharpness of the tip apex and repeatability of images depends on mechanical strength of tip material. During last decades, a variety of techniques and processes have been developed for fabrication of different metallic tips made from tungsten, platinum, platinum–iridium, gold, and silver. Electrochemical etching process is the most popular method for fabrication of nanotips with desired quality, reliability, and reproducibility and tungsten is normally the first choice for fabrication of STM tips as it has a high mechanical strength as well as a good electrical conductivity. Fabrication of STM tungsten tip by using electrochemical etching method and tip characterization has been the subject of several researches. Nevertheless, to our knowledge, effect of voltage type (AC/DC), time delay in turning off the voltage, tungsten wire diameter, environmental vibrations, electrolyte type, cathode material, and perpendicularity of tungsten wire (toward electrolyte surface) on the tip sharpness have not been studied so far. In this paper, effects of these parameters on the tip shape and sharpness are investigated. A proper set-up for STM tungsten nanotip fabrication by using electrochemical etching method is presented.
8 citations
TL;DR: In this paper, the authors measured the conductivity of multi-walled carbon nanotubes and onion-like carbon (OLC) in different gaseous media: helium, air, oxygen, hydrogen and methane.
Abstract: We measured the conductivity of multi-walled carbon nanotubes (MWNTs) and onion-like carbon (OLC) in different gaseous media: helium, air, oxygen, hydrogen and methane. The MWNTs had different mean outer diameters varied from 5 to 15 nm. The OLC was synthesized at 1400–1850 K. The adsorption of nitrogen, oxygen, hydrogen and methane leads to decrease of conductivity because these gases are the donors of electron for semi-metallic band structure of investigated objects.
TL;DR: The photophysical properties of traditional fluorescent labels and the comparatively advantageous properties of quantum dots are discussed, which make them attractive probes in biological applications and prime candidates for further research and development in the field of solid-phase immunoassay and cell analysis.
Abstract: The development of new fluorophores has experienced a tremendous advance over the last two decades. Here, we discuss the photophysical properties of traditional fluorescent labels and the comparatively advantageous properties of quantum dots. The unique spectral properties of quantum dots, such as their large Stokes shifts and exceptional brightness, make them attractive probes in biological applications and prime candidates for further research and development in the field of solid-phase immunoassay and cell analysis.
TL;DR: In this article, a study of the growth of CdTe nanoparticles in novel glass system was presented, where different techniques were used: differential thermal analysis (DTA), X-ray diffraction (XRD), optical absorption spectra and FTIR spectroscopy.
Abstract: A study of the growth of CdTe nanoparticles in novel glass system was presented. The effect of the growth of CdTe nanocrystals on the glass structure was been investigated by different techniques: differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, and optical absorption spectra and FTIR spectroscopy. The evolution of X-ray diffraction at different annealing temperatures is studied and showed that the ratios of the elemental of semiconductor constituents decrease with increasing annealing temperatures. Furthermore X-ray analysis showed that the sizes of the nanoparticles increase with increasing annealing temperatures. The investigation of the absorption spectra and calculation of nanoparticles sizes from the first absorption maximum are very close to the sizes calculated by Sherrer equation. Finally, FTIR spectroscopy explained the exchangeable effects between the glass matrix and semiconductor nanoparticles during the growth of nanoparticles.
TL;DR: In this article, the aligned hollow piezoelectric poly (viniliden fluoride) (PVDF) nanofiber was prepared by co-axial electrospinning.
Abstract: The aligned hollow piezoelectric poly (viniliden fluoride) (PVDF) nanofiber was prepared by co-axial electrospinning. Beaded free finer aligned hollow nanofibers have diameter range between 80 and 300 nm. Surface roughness and crystal structure of nanofiber fibers were successfully controlled by using special ionic additives. Furthermore, crystalinity of aligned fiber was evaluated by differential scanning calorimetry. Fourier transforms infra red (FTIR), polarized FTIR, and wide angle X-ray diffraction analysis of fiber showed that the aligned PVDF nanofiber had rich content β-phase crystal structure, and PVDF molecule orientation was along fiber axis. Advanced discussion will be exposed in this paper such as effect of electrospinning speeds on morphology, fiber diameter, crystalinity, and crystal structure of hollow PVDF nanofiber. Piezoelectric nanofiber has great potential application in advanced sensor and actuator.
TL;DR: In this paper, the effect of the diameter of a carbon nanotube (CNT) on its specific heat was theoretically simulated and it was shown that transversal phonon modes play an important role in the increasing of specific heat with respect to the diameter.
Abstract: Specific heat of carbon nanotube (CNT) is affected by its diameter. Increasing of the CNTs diameter increases its specific heat. This phenomenon is due to transversal acoustic phonon modes. The contribution to specific heat from TA modes varies linearly with temperature and becomes saturated after specific temperature. In this paper, the effect of CNTs diameter on the specific heat is theoretically simulated. The result indicates that transversal phonon modes play an important role in the increasing of specific heat with respect to the diameter.
TL;DR: In this article, the distribution of hydrogen atoms inside a metallic nanoparticle was investigated by changing length and energy parameters of metal-H bonds, and hydrogen atoms diffused into the particle and distributed homogeneously in case of weak metal−H bonds.
Abstract: Hydrogen storage in a metallic nanoparticle was simulated by classical molecular dynamics. Distribution of hydrogen atoms inside nanoparticle was investigated by changing length and energy parameters of metal–H bonds. Hydrogen atoms diffused into the particle and distributed homogeneously in case of weak metal–H bonds. In case of strong metal–H bonds, a hydrogen-rich surface layer was observed which suppresses the inward diffusion of hydrogen atoms. Structural modification of nanoparticle accompanied by grain boundary formation due to hydrogen loading was also observed. These variations in dynamical and structural features are considered to affect the hydrogen storage properties in nanoparticles.
Journal Article•
TL;DR: In this paper, the structure of the nanoparticles dispersed in the ferrofluid was studied using XRD, FTIR, XPS, and TGA analysis, while morphology and size of nanoparticles were determined by TEM.
Abstract: High-quality hydrophobic or hydrophilic ferrofluid based on magnetite (Fe3O4) nanoparticles can be synthesized by one-pot direct synthesis which involves thermolysis of Iron(III) acetylacetonate, Fe(acac)3 in hydrophobic or hydrophilic stabilizing agent, respectively. The structure of the nanoparticles dispersed in the ferrofluid was studied using XRD, FTIR, XPS, and TGA analysis, while morphology and size of the nanoparticles were determined by TEM. The magnetic properties of the samples were measured using VSM and SQUID measurement. The results show that oleylamine (OM) and tri(ethylene glycol) (TREG) coated Fe3O4 nanoparticles which are well stabilized in hydrophobic and hydrophilic ferrofluid, respectively, are relatively monodisperse, single crystalline and superparamagnetic in nature with the blocking temperature at around 100 K.
TL;DR: In this paper, a theoretical model for quantitative analysis of decrease in thermal conductivity (κ) by embedding ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors was proposed.
Abstract: We evolve a theoretical model for quantitative analysis of decrease in thermal conductivity (κ) by embedding ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors. The lattice thermal conductivity by incorporating the scattering of phonons with defects, grain boundaries, electrons, and phonons in the model Hamiltonian are evaluated. It is noticed that the ErAs nanoparticles provide an additional scattering mechanism for phonons. The embedding of ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors, the phonon scattering with point defects and grain boundaries become more efficient, which cause in the decrease of thermal conductivity up to half of its value of pure crystal. Conclusively, the temperature dependent of thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers. Numerical analysis of thermal conductivity from the present model shows similar results as those revealed from experiments.
TL;DR: In this article, a quasiharmonic lattice dynamics method is employed to study the thermodynamic functions of binary (mixed) H2-CH4 hydrates of cubic structure II (sII) and hexagonal structure H (sH) and it is shown that at divariant equilibrium "gas phase-gas hydrate" with increasing pressure the filling of large cavities by hydrogen proceeds gradually from single filling to the maximal number of hydrogen molecules in clusters included in large cages (four in sII and five in sH).
Abstract: Storage of hydrogen as hydrogen hydrate is a promising alternative technology to liquefied hydrogen at cryogenic temperatures or compressed hydrogen at high pressures. In this paper, computer simulation is performed based on the solid solution theory of clathrates of van der Waals and Platteeuw with some modifications that include in particular the account of multiple cage occupancies and host relaxation. The quasiharmonic lattice dynamics method employed here gives the free energy of clathrate hydrate to first order in the anharmonicity of intermolecular potential and permits to take into account quantum zero-point vibration of host lattice and hydrogen in the cages. It is employed to study the thermodynamic functions of binary (mixed) H2–CH4 hydrates of cubic structure II (sII) and hexagonal structure H (sH). It is shown that at divariant equilibrium "gas phase–gas hydrate" with increasing pressure the filling of large cavities by hydrogen proceeds gradually from single filling to the maximal number of hydrogen molecules in clusters included in large cages (four in sII and five in sH) preserving stability of the hydrogen–methane hydrates sII and sH. The results show that mass fraction of hydrogen in the mixed sH hydrate is significantly lower than in the mixed sII hydrate. Pressure of monovariant equilibrium "IceIh–gas phase–mixed sII hydrate" with increasing methane concentration in the gas phase lowers in comparison with the pressure of pure hydrogen hydrate formation. For the mixed hydrogen + methane sH hydrates, it was demonstrated that thermodynamic stability depends on the filling degree of small cavities by methane molecules and stability area shifts to lower pressure with increasing filling.
TL;DR: In this article, Nanocrystalline Pd electrocatalyst promoted with transition metal oxide (Co3O4, NiO, and CoNiOx) is successfully synthesized on high surface carbon support by using intermittent microwave heating (IMH) method.
Abstract: Nanocrystalline Pd electrocatalyst promoted with transition metal oxide (Co3O4, NiO, and CoNiOx) is successfully synthesized on high surface carbon support by using intermittent microwave heating (IMH) method. The physical properties of the catalysts are characterized by XRD, TEM, and EDX. The results show that there is no significant microstructure change between Pd and Pd-oxide electrocatalysts and the particle sizes are in the range 5.8–3.9 nm. The linear sweep voltammogram and chronoamperometry results for the electro-oxidation of ethanol show that Pd-oxide/C electrocatalysts exhibit much better electrochemical activity and stability as compared with pure Pd/C electrocatalyst. The results show that Pd–CoNiOx/C exhibits the best stability and highest electro-oxidation activity, indicating the promising potential as an alternative electrocatalysts for the direct ethanol fuel cells.
TL;DR: In this paper, the authors discuss some recent progresses in the design of complex nanostructures through chemical routes, emphasize particularly on metal oxides, and describe more recent work on the use of different methods to synthesize a wide range of complex nano-structures, including hierarchical structures, heter-ructures, as well as oriented nanowires and nanotubes.
Abstract: Nanostructured materials with controlled architectures are desirable for many applications, among which, metal oxides are especially important in optics, electronics, biology, catalysis, and energy conversions. Various chemical routes have been widely investigated for the synthesis of nanostructured metal oxide particles and films. More recently, deliberately designed chemical strategies have been used to produce particles and films composed of more complex crystal structures. In this paper, we discuss some recent progresses in the design of complex nanostructures through chemical routes, emphasize particularly on metal oxides. We first review some basic concepts involved in the fabrication of complex nanostructures, including crystal nucleation and growth, shape controlling and ripening process. We then describe more recent work on the use of different methods to synthesize a wide range of complex nanostructures, including hierarchical structures, heterostructures, as well as oriented nanowires and nanotubes. Such purposely built materials are designed, and engineered to match the physical, chemical, and structural requirements of their applications.
TL;DR: In this paper, the adsorption of cytosine on graphene surface was studied using density functional theory with local density approximation, and it was shown that the sensitivity of graphene-based bio-sensors could be drastically improved by introducing appropriate metal atoms.
Abstract: The adsorption of cytosine on graphene surface is studied using density functional theory with local density approximation. The cytosine is physisorbed onto graphene through π–π interaction, with a binding energy around -0.39 eV. Due to the weak interaction, the electronic properties of graphene show little change upon adsorption. The cytosine/graphene interaction can be strongly enhanced by introducing metal atoms. The binding energies increase to -0.60 and -2.31 eV in the presence of Li and Co atoms, respectively. The transport behavior of an electric sensor based on Co-doped graphene shows a sensitivity one order of magnitude higher than that of a similar device using pristine graphene. This work reveals that the sensitivity of graphene-based bio-sensors could be drastically improved by introducing appropriate metal atoms.
TL;DR: In this paper, the effect of composition on the optical absorption and photoluminescence spectra of the semiconductor quantum dots (QDs) of CdSxSe1-x embedded in borosilicate glass matrix has been studied.
Abstract: The effect of composition on the optical absorption and photoluminescence (PL) spectra of the semiconductor quantum dots (QDs) of CdSxSe1-x embedded in borosilicate glass matrix has been studied. It is observed that the first exciton absorption peak shifts from 2.62 to 2.21 eV and the PL peak shifts from 2.16 to 1.87 eV as the composition of selenium increases from 8 to 92 wt%. Samples having higher concentration of sulfur are found to have higher PL peak intensity, which is interpreted to be due to high concentration of shallow traps in the sulfur-rich samples. Absorption coefficient goes on increasing as the selenium content increases. This may be attributed to the fact that selenium has higher atomic size as compared to that of sulfur.
TL;DR: In this paper, the effects of bending moment on the structure of double-walled carbon nanotubes (DWCNTs) were considered and the bending stability of inner and outer tubes was investigated.
Abstract: This paper considers the effects of bending moment on the structure of double-walled carbon nanotube (DWCNT). Two types of DWCNTs with almost the same aspect ratio (length/radius) are selected; also continuum modeling is utilized to study the bending stability of inner and outer tubes. As a result of the van der Waals interaction between adjacent tubes the critical bending moment of inner tube is higher than this moment of outer tube which is indicated from the obtained results of this research; thus, achieving higher reliability in nanostructures, the critical bending moment of outer tube should be taken into account.
TL;DR: In this paper, temperature and magnetic field dependences of conductivity of multi-walled carbon nanotubes (MWNTs) with different average outer diameter were investigated, and the dependence of constant of electron-electron interaction λ versus curvature of graphene layers in MWNTs was determined.
Abstract: We investigated temperature and magnetic field dependences of conductivity of multi-walled carbon nanotubes (MWNTs) with different average outer diameter. We separated out the quantum corrections to magnetoconductivity for interaction electrons and determined the dependence of constant of electron–electron interaction λ versus curvature of graphene layers in MWNTs.
TL;DR: In this paper, the SU-8/SiO2/PMMA tri-layer technique was applied for the duplication of imprint templates, originally fabricated by e-beam lithography (EBL) followed by reactive ion etch (RIE), using a SU- 8/Si O2/PMA trilayer technique.
Abstract: Nanoimprint lithography (NIL) technology has aroused great interests in both academia and industry due to its high resolution, low-cost, and high-volume nanopatterning capability. And as an expoxy resin-based negative amplified photoresist, SU-8 is an ideal candidate for NIL because of its low-glass-transition temperature, low-volume shrinkage coefficient, and good optical properties. In this reviewing paper, we highlight the major technical achievements in NIL on epoxy resin and its applications for bio- and nanophotonic structures. NIL was also applied for the duplication of imprint templates, originally fabricated by e-beam lithography (EBL) followed by reactive ion etch (RIE), using a SU-8/SiO2/PMMA tri-layer technique. And nanoimprint properties were systematically investigated for optimization. The developed nanoimprint process for different applications indicates promising industrial potentials in the next generation lithography resolution.
TL;DR: In this article, a GaAs/AlGaAs-based quantum well was proposed to achieve high spin polarization without the need for less commonly used materials with high g-factors required by previously proposed semiconductor-based systems.
Abstract: We present a GaAs/AlGaAs-based quantum well device capable of achieving an appreciable spin polarization coupled with high electron transmission. Our numerical results indicate that the device is able to achieve a high spin polarization without the need for less commonly used materials with high g-factors required by previously proposed semiconductor-based systems. The electron transmission and spin polarization amplitude of our structure is found to be robust to the length of the parabolic well, which could ease the fabrication of such structures in practical applications.
TL;DR: In this paper, hydrogen adsorption coverage, isosteric heat, binding energy, hydrogen desorption, and readsorption were calculated for both internal and external surfaces of nanotube at several temperatures from 77 K up to 400 K.
Abstract: Hydrogen adsorption isotherms for (8, 0) platinum-decorated single-walled carbon nanotube were studied using molecular dynamics simulation. Adsorption isotherms were obtained for both internal and external surfaces of nanotube at several temperatures from 77 K up to 400 K. The results were compared with the bare nanotube at the same conditions. Adsorption coverage, isosteric heat, binding energy, hydrogen desorption, and readsorption were calculated for both internal and external surfaces of nanotube. At low temperatures, hydrogen molecules were adsorbed significantly, but at higher temperatures, thermal energies reduced this capacity. Under the same conditions, the platinum-decorated single-walled carbon nanotube hydrogen adsorption is significantly higher than the bare one.
TL;DR: In this paper, thin sheets like carbon nanostructures and carbon nanoparticles have been effectively synthesized with CH4 and Ar as precursors at low temperature (< 400°C) by inductively coupled radio frequency plasma enhanced chemical vapor deposition on silicon and glass substrates.
Abstract: In this study, thin sheets like carbon nanostructures and carbon nanoparticles have been effectively synthesized with CH4 and Ar as precursors at low temperature (< 400°C) by inductively coupled radio frequency plasma enhanced chemical vapor deposition on silicon and glass substrates. The surface morphology and chemical composition were studied by atomic force microscopy (AFM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. AFM studies show that the nanoparticles roughly about 70 to 80 nm in diameter surrounded by nanosheets. Nanosheets are about 100 nm in thickness, which attain approximately 1.75 μm lengths. EDS results revealed that the atomic percentage of carbon in the particle like structure is more than that in the nanosheet like structures.