Structure of Higher Fullerenes and Growth Mechanisms
According to Euler's theorem on closed polyhedrons (refer to Section 4.2.1), every fullerene composed of five- and six-membered rings contains 2 (10 + M) C-atoms, and the resulting cage is made of exactly 12 penta- and M hexagons. The smallest conceivable fullerene accordingly is C20 (M 0). While this molecule could not be isolated experimentally so far, the related hydrocarbon C20H20 is known. It features the expected pentagon-dodecahedral structure. With M increasing, the number of possible...
MEMS Technology for Satellite Communications and Space Systems Applications
Wireless satellite communications and space-based sensors are the major beneficiaries of the MEMS technology. Minimum size, power consumption, and high reliability are the critical requirements for both the applications, which can be satisfied by deploying MEMS-based devices and sensors. MEMS technology conserves energy and minimizes power consumption, weight, and size. RF-MEMS devices such as switches, phase shifters, switched antennas, filters, and amplifiers have become critical to...
Arc Discharge Production of SWNTs
SWNTs are produced in an arc process utilizing covaporization of graphite and metal in a composite anode 30,31 commonly made by drilling an axial hole in the graphite rod and densely packing it with a mixture of metal and graphite powders. Various pure elements and mixtures have been used to fill the rod, including Fe, Co, Ni, Cr, Mn, Cu, Pd, Pt, Ag, W, Ti, Hf, La, Ce, Pr, Nd, Tb, Dy, Ho, Er, Y, Lu, Gd, Li, B, Si, S, Se, Zn, Sn, Te, Bi, Cd, Ge, Sb, Pb, Al, In, Fe Co, Fe Ni, Fe Co Ni, Co Ni, Co...
Amplitude Modulation Tapping Mode AFMs
In tapping mode, or AM-AFM, the cantilever is excited externally at a constant frequency close to its resonance. Oscillation amplitude and phase during approach of tip and sample serve as the experimental observation channels. Figure 15.6 shows a diagram of a typical tapping-mode AFM setup. The oscillation amplitude and the phase (not shown in diagram) detected with the photodiode are analyzed with a lock-in amplifier. The amplitude is compared to the set-point, and the difference or error...
Thin Film Deposition and Doping
Thin-film deposition and doping are used extensively in micro nanofabrication technologies. Most of the fabri Fig. 5.2 Schematic drawing of the photolithographic steps with a positive photoresist (PR) cated micro nanostructures contain materials other than that of the substrate, which are obtained by various deposition techniques, or by modification of the substrate. The following is a list of a few typical applications for the deposited and or doped materials used in mi-cro nanofabrication...
Using Wet Etch and Wafer Bonding
The use of anisotropic wet etchants to remove silicon can be regarded as the beginning of the micromachining era. Back side etch was used to create movable structures such as beams, membranes, and plates, Fig. 5.20. Initially, the etching was timed to create a specified thickness. However, this technique proved inadequate in creating thin structures (< 20 m). Subsequent use of various etch stop techniques allowed the creation of thinner membranes in a more controlled fashion. As mentioned in...
MEMS Varactors or Tunable Capacitors
MEMS varactors are also known as tunable capacitors because of their ability to provide wideband tuning capability in radio frequency (RF) and microwave regions. MEMS varactors are best suited for microwave and MM-wave phase shifters, wideband tuning voltage-controlled oscillators (VCOs), RF amplifiers, and reconfigurable RF filters. Critical elements of a MEMS varactor are shown in Figure 8.1. It is important to mention that the MEMS varactor provides ultra-wideband tuning capability because...
Melt Quenching Technique
The melt quenching technique is widely used to prepare glasses and glass-ceramics. It needs higher temperature compared to that required for the sol-gel technique, but it takes less time. The TiO2, BaTiO3, SrTiO3, doped vanadate glasses or the VP glasses or other low melting TMO glasses VP type base glasses , in general, can be prepared by a fast quenching method 48, 50 . For example, VP glass can be used to prepare a typical 80V205-20P205 xTiO2 type FGNC with different concentrations of TiO2 x...
Structure of the 111Plane
The (111)-face represents the natural cleavage plane of bulk diamond, whereas in diamond films its importance stands back a bit behind that of the (100)-face. In theory, two (111)- surfaces can be conceived with one of them featuring a single unsaturated bonding site per superficial carbon atom and with the other exhibiting methyl-like structures with three dangling bonds. The latter, however, is much less favorable from an energetic point of view, so only the reconstruction actually observed...
OVD Foil Microstructures
The first application of OVD technology as an anti-counterfeiting feature was the result of the adaptation of existing holographic technology to high volume manufacture by direct embossing onto foil and the application of that foil onto the security document by a hot stamping process. The security hologram was developed initially by the American Bank Note Company through its subsidiary, American Bank Note Holographics (ABNH) and was first adopted by MASTERCARD in 1982 in the form of a 2D 3D...
Grating Light Valve GLV
Silicon Light MachinesTM and Grating Light ValveTM are trademarks of Silicon Light Machines. Silicon Light Machines (SLMTM) has developed silicon chip based display architecture that can be used for many imaging applications including high-definition televisions, movie projection and high-performance desktop display systems. SLM was formed to commercialise a broad range of products based on patented Grating Light Valve (GLVTM) technology. GLVTM, an optical MEMS device built onto silicon wafers,...
Overview of the lattice Boltzmann method for nano and microscale fluid dynamics in materials science and engineering
Max-Planck-Institut f r Eisenforschung, Max-Planck-Strasse 1, 40237 D sseldorf, Germany E-mail raabe mpie.de Received 15 March 2004, in final form 2 August 2004 Published 16 September 2004 Online at stacks.iop.org MSMSE 12 R13 doi 10.1088 0965-0393 12 6 R01 The article gives an overview of the lattice Boltzmann method as a powerful technique for the simulation of single and multi-phase flows in complex geometries. owing to its excellent numerical stability and constitutive versatility it can...
Advantages of Sol Gel Process
Sol-gel technique, as a method for synthesizing thin- or thick-film gas sensor, offers several advantages 1, 2 i The sol-gel technique is simpler and cheaper than others, ii it allows an easy coating of large and complex shaped substrates if the angles are not too sharp , iii the process is inexpensive with respect to the initial investment of the production plant and the running cost, iv it produces no perturbations of devices in the case of deposition on top, v it offers easy control of film...
Pore Volume of Nanotubes
Figure 3.6a shows the differential pore-volume distributions obtained from the desorption of nitrogen curve using the BJH algorithm, for two titanate nano-tube samples characterised by different average tube diameters. The curves have a bell-like shape, and the maxima corresponds to pore sizes of 4 to 20 nm, relating this material to pores with a mesoporous range. In general, methods of nitrogen adsorption and, in particular, the BJH pore size distribution technique are suitable for...
Degenerate Semiconductors
In Section 3.4 we gave the name non-degenerate semiconductors to those for which the Fermi level EF is located in the gap at an energy of about 3kT or more away from the band edges. Since for these semiconductors, classical statistics could be applied, we derived simple expressions, Eqs (3.12) and (3.15), for the concentration of electrons and holes, respectively. Under these premises we also derived Eqs (3.24), (3.25), and (3.26) which give the location of the Fermi level for n-type, p-type,...
Parabolic And Triangular Quantum Wells 441 Parabolic well
The case of the parabolic well is well known in solid state physics since the vibrations of the atoms in a crystal lattice, whose quantification gives rise to phonons, are described in a first approximation by harmonic oscillators. In addition, a magnetic field applied to a two-dimensional electron system gives rise to a parabolic potential, and the electrons oscillate at the so-called cyclotron frequency. Parabolic quantum well profiles can also be produced by the MBE growth technique. In this...
Molecular Building Blocks
Two different methods are envisioned for nanotechnology to build nanostructured systems, components and materials One method is named the top-down approach and the other method is named the bottom-up approach 1 . In the top-down approach the idea is to miniaturize the macroscopic structures, components and systems towards a nanoscale of the same. In the bottom-up approach the atoms and molecules constituting the building blocks are the starting point to build the desired nanostructure. Various...
Stern-Grahame model
The Gouy-Chapman model of EDL includes some unrealistic cases. For example, the ions are assumed as point charges and any specific effects related to the ion size are neglected. Therefore the adsorption densities on the solid surface calculated for moderate surface potentials and ionic strength values are so high that they are physically impossible. Also, the solvent is assumed to have continuous properties everywhere in solution however, its properties such as the dielectric constant and the...
Lattice Transformations and Defects
The lack in space filling that results when composing MTPs of regular fcc tetrahedral subunits raises the question of whether the lattice of some or all of these subunits may adopt a slightly changed state of uniform distortion. To allow for the absence of spatial discontinuities in MTPs, some kind of structural modification or lattice defect is needed. This may be brought about by elastic strains acting on the tetrahedral subunits as first described by S. Ino to calculate their stability 17 ....
Nanopore Containment Of Magnetic Particles
Another area of ongoing research in nanomagnctism involves developing magnetic materials by filling porous substances with nanosized magnetic particles. In fact, there are actually naturally occurring materials having molecular cavities filled with nanosized magnetic particles. Ferritin is a biological molecule, 25 iron by weight, which consists of a symmetric protein shell in the shape of a hollow sphere having an inner diameter of 7.5 nm and an outer diameter of 12.5 nm. The molecule plays...
Concept 1 Lessons From the SCurve
The first concept is that of the S-curve. Introduced by Richard Foster, the S-curve describes the relationship between the investment of resources in a technology or process and the resulting performance produced by that investment (Figure 1-1).UH It is referred to as an S-curve because when the results are plotted, the resulting figure typically takes the shape of the letter S. Figure 1-1. An example of an S-curve. Figure 1-1. An example of an S-curve. In an early stage, as effort is ramping...
Graphite and C60
As an illustration of results which can be derived using techniques described in the previous section, we present now some spectroscopic results on quasi two-dimensional graphite and the quasi zero-dimensional fullerene Ceo (for a recent review on fullerenes, see 9 ). These results on graphite and C60 will help to understand the electron spectroscopy results on the quasi one-dimensional carbon nanotubes. PES spectra of graphite 10 are shown in Fig. 2. For EB < 7.5 eV, the spectral weight is...
The Importance of Nanoscale
The Greek word nano (meaning dwarf) refers to a reduction of size, or time, by 10-9, which is one thousand times smaller than a micron. One nanometer (nm) is one billionth of a meter and it is also equivalent to ten Angstroms. As such a nanometer is 10-9 meter and it is 10,000 times smaller than the diameter of a human hair. A human hair diameter is about 50 micron (i.e., 50x 10-6 meter) in size, meaning that a 50 nanometer object is about 1 1000th of the thickness of a hair. One cubic...
Graphite and Its Structure
The structure of graphite had been elucidated from 1917 on by Debye, Scherrer, Grimm, Otto, and Bernal. It is characterized by a succession of distinct so-called graphene layers that spread over an xy-plane. They are stacked in a z-direction, and there are only weak van der Waals interactions among them (Figure 1.7). Within one graphene layer, the carbon atoms are situated at the corners of regular hexagons that constitute a two -dimensional lattice. From each C -atom there are three o-bonds...
Ropes of Nanotubes
As discussed above, an isolated (n, n) carbon nanotube has two linearly dispersing conduction bands which cross at the Fermi level forming two Dirac points, as schematically presented in Fig. 19a. This linear band dispersion in a one-dimensional system gives rise to a finite and constant density of electronic states at the Fermi energy. Thus, an (n, n) tube is a metal within Fig. 19. Band crossing and band repulsion. (a) Schematic band structure of an isolated (n, n) carbon nanotube near the...
Trilayer graphene is a semimetal with a gatetunable band overlap
Yamamoto1, J. B. Oostinga23, A. F. Morpurgo3 and S. Tarucha1'45 Graphene-based materials are promising candidates for nano-electronic devices1-14 because very high carrier mobilities can be achieved without the use of sophisticated material preparation techniques1. However, the carrier mobilities reported for single-layer and bilayer graphene are still less than those reported for graphite crystals at low temperatures, and the optimum number of graphene...
Electrical and Piezoresistive of CNTs
The unique electrical properties of CNTs are to a large extent derived from their 1-D character and the peculiar electronic structure of graphite. Resistance occurs when an electron collides with some defect in the crystal structure of the material through which it is passing. The defect could be an impurity atom, a defect in the crystal structure, or an atom vibrating about its position in the crystal. Such collisions deflect the electron from its path. But the electrons inside a CNT are not...
Band Structure and Density of States of Carbon Nanotubes
It is essential to give a correct and conclusive description of the electronic properties of carbon nanotubes to get an understanding of their broad potential for applications. Chemists and physicists have developed two fundamentally different concepts of the matter. They are either based on considering electrons in molecular orbitals, especially in frontier orbitals, and on examining the n-system, or they pursue a solid-state physical approach that employs density-of-state functions and the...
Nanostructured Crystals
In this section we discuss the properties of crystals made of ordered arrays of nanoparticles. There are some instances of what might be called natural nanocrystals. An example is the 12-atom boron cluster, which has an icosahedral structure, that is, one with 20 faces. There are a number of crystalline phases of solid boron containing the B 2 cluster as a subunit. One such phase with tetragonal symmetry has 50 boron atoms in the unit cell, comprising four B12 icosahedra bonded to each other by...
Nanometers Micrometers Millimeters
A nanometer, 10 9m, is about ten times the size of the smallest atoms, such as hydrogen and carbon, while a micron is barely larger than the wavelength of visible light, thus invisible to the human eye. A millimeter, the size of a pinhead, is roughly the smallest size available in present day machines. The range of scales from millimeters to nanometers is one million, which is also about the range of scales in present day mechanical technology, from the largest skyscrapers to the smallest...
Nanodiamond Applications
Being extremely small and with high amount of surface atoms, nanodiamond has diversified applications. Some applications involve using the superhard properties of diamond. The others may adapt low frictional coefficient of diamond (Table 7.1). 7.1 LUBRICATION OF ENGINE OIL AND MACHINE GREASE Nanodiamond can reduce significantly the frictional coefficient by coating on the sliding surface. The nanodiamond coating reduces the contact area. Moreover, the inertness of the diamond surface reduces...
Silicon Wafer Dry Etching Notching Effect Benefit -prevent -prevention
Where, the tensors Eijkl and Sjkl are replaced by Em,n and Sm,n, respectively. This can be obtained by substituting the indices ij m and kl n. In a cubic structure it can be considered that x, y and z directions are replaced by 11, 22, 33 and the corresponding planes xy 12 and 21, xz 13 and 31, yz 23 and 32 are in symmetry. With this representation the stress and strain components can be represented as x E11 x + E12 y + E13 z + E14 xy + E15 xz + E16 yz Sx S11CTx + S12ay + S13 z + S14rxy +...
Wetetched Silicon Structures
Microsystems technology relies on anisotropic wet etching of silicon for many major applications. Bulk micromechanics depends on silicon crystal plane-dependent etching, and many surface micromechanical and SOI devices make use of silicon wet etching for auxiliary structures, even though main device features are defined by plasma etching. Because < 100> silicon is the workhorse of microsystems, the discussion concentrates on it. Both < 110> and < 111 > etching will be reviewed...
Float zone FZ crystal growth
If high purity or oxygen-free silicon is needed, float zone (FZ) crystal growth is used. In the FZ-method, a polysilicon ingot is placed on top of a single-crystal seed. The polycrystalline ingot is heated externally by an RF coil, which locally melts the ingot. The coil and the melted zone move upwards, and a single crystal solidifies on top of the seed crystal. The highest FZ-silicon resistivities are of the order of 20 000 ohm-cm, compared to 100 to 1000 ohm-cm for CZ. Because there is no...
Wet Etching Processes
Wet etching processes include a transfer of the removed solid state material into the liquid phase. Therefore, a chemical species is generated that is soluble (and therefore mobile) in the liquid phase 37 38 . Metals and semiconductors are transformed into cations or soluble coordinated compounds oftheir cations, through the involvement of local electrochemical processes. The standard open-circuit etching process compensates the local currents by reduction of oxidizing agents at the metal or...
Ion Beam Etching
(1) diode reactors with horizontal target plates for single-wafer processing, (2) triodes with an extra electrode used for increased ion bombardment, and (3) hexodes designed for batch processing in which the vertically arranged cathode has the shape of a hexagon surrounded by the cylindrical chamber walls forming the anode. A disadvantage of the contact plasma reactors is that the flux of all the impinging species at the sample surface is difficult to control. A way to improve this is by way...
Electron Beam Resists
EBL is classified as a reactive processing in terms of Electron Beam Processing. In this process, ionization and excitation of constituent molecules of the material occur during the scattering of the incident electrons. Some excited molecules lose their energy by collisions with other molecules and change into radicals. All these ions, excited molecules, radicals, and the secondary electrons are called active species that induce chemical reactions inside the material. Electron beam resists are...
Arc Discharge Production of MWNTs
3.2.1 General Technical Features of the Production Process The carbon arc technique for generating MWNTs appears very simple, but obtaining high yields of tubes is difficult and requires careful control of experimental conditions. In the most common laboratory scale production scheme, the direct current (DC) arc operates in a 1- to 4-mm wide gap between two graphite electrodes 6 to 12 mm in diameter that are vertically or horizontally installed in a water-cooled chamber filled with helium gas...
Introduction To Bridging Ligands
Bridging ligands have received much interest recently due to their ability to couple metal centers in a covalent manner resulting in polymetallic complexes that often possess new and interesting properties. Bridging ligands of the type discussed herein bind to each metal through one or more donor atoms forming a coordinate covalent c-bond.
Variant 1 Classical styrene synthesis using an iron oxide catalyst
Styrene is synthesized in an industrial process that has been known for roughly 60 years the dehydrogenation of ethylbenzene. The dehydrogena-tion of ethylbenzene to produce styrene is a reversible endothermic balance reaction (Lieb & Hildebrand 1982) C6H5C2H5 C6H5C2H3 + H2 AH600 c 124.9 kJ mol (1) The dehydrogenation of ethylbenzene to produce styrene takes place at temperatures of 600 C in an ethylbenzene-water mixture and is assisted by potassium-promoted iron oxide catalysts. Along with...
In New Jersey, Solar Panels Beat the Stock Market with 324% Return on Investment
Say you live in New Jersey and have 25,500 to invest today. Where is the best place to put it for the next 15 years Stocks Bonds Try solar panels on your roof.Let's face it for many people, buying solar panels for the home is a serious investment. Here at 1BOG we knew that solar was a good investment in New Jersey, but we wanted provide our members with a better analysis of the long-term ROI (Return On Investment). Right now, an investment of 25,500 in a 7.
Zeta Potential For Gold Au
Iff7 106 105 104 103 102 101 Concentration of electrolyte equivalents per liter Fig. 3 Zeta potential profile of a positively charged alumina surface in the presence of various ions. Source From Ref. 3 . covalent bonding with surface atoms or be more physical, e.g., van der Walls forces between the ion and the surface or between the hydrocarbon chains of surfactant ions adsorbed. 3 Isoelectric Point and or Point of Zero Charge Although the isoelectric point iep and the point of zero charge pzc...
Bulk Micromachining
Bulk micromachining is one of the earliest processes in the field of microsystem technology 187-276 . While there are many different types of bulk micromachining, the basic concept is to create features out of a substrate. In general, a silicon, SOI, or glass wafer serves as the substrate material and the structures are created by way of removing (etching) the parts of the wafer that are not wanted, leaving the desired structure behind. Typically, this is done through a sequence of...
Historical High Pressure Synthesis Of Diamond
Numerous methods using high pressure technology have been invented to synthesize diamond in the past. In fact, high pressure technology was developed largely because of the need to synthesize diamond. Hannay developed sealed steel tubes that could contain organic volatiles at high temperatures to about 0.2 GPa (1880). Parsons built a piston-cylinder apparatus that could bring pressures up to 1 GPa (1888). The Nobel laureate Moissan quenched molten steel to attain a pressure of about 0.5 GPa...
Near Field Scanning Optical Microscopy
A TopoMetrix Aurora-2 NSOM was used for our experiments. A schematic of the NSOM system is shown in Figure 12.3. The fiber-optic probe (aperture size 60-100 nm) attached to a piezoelectric tuning fork was mounted on the removable Aurora-2 microscope head and positioned above the sample. A resonating frequency ranging between 90 and 100 kHz was selected with less than 1 nm lateral amplitude at the probe end.
Near Field Scanning Optical Microscopy for Bioanalysis at Nanometer Resolution
Viallet, and Tuan Vo-Dinh The nondestructive imaging of biomolecules in nanometer domains in their original location and position as adsorbed or deposited on a surface is of garners considerable experimental interest. Near-field scanning optical microscopy (NSOM) is an emerging technique with its astonishing resolving power of X and greater than the aperture. Thus, subwavelength details of the image are lost. Over the past decade, NSOM has evolved into a new frontier...
Graphite and Related Materials Rdk
Graphite may be the thermodynamically most stable modification of carbon. Still it is chemically attacked more easily than diamond due to its layered structure and the comparatively weak interaction between the graphene sheets. Altogether the graphite's reactivity toward many chemicals is rather low nevertheless. With chlorine, for example, it does not react at all under usual conditions, and even with fluorine reaction occurs only at more than 400 C. Suitable performance yields the...
Characterising the Surface Micromachining Process
From the definition of the surface micromachining process, one can note that deposition of materials layers is used to create the desired structure of a typical device. Fig. 6.3 illustrates the surface micromachining process. (d) Pliotomasking Fig. 6.3 Surface micromachining process A silicon substrate is used as the ground plane. The first step in the surface micromachining process is the deposition of a thin isolation layer. This layer is deposited with a dielectric material such as silicon...
Superlattices
The concept of a superlattice The concept of the superlattice (SL) was proposed by Leo Esaki and coworkers in the late 60s and later fabricated by molecular beam epitaxy (MBE) techniques. Superlattices can be considered one of the most important man-made or artificial materials. A superlattice consists of a periodic set of MQW in which the thickness of the energy barriers separating the individual wells is made sufficiently small. As the barriers become thinner, the electron wave...
The Structure And Chemical Reactivity Of Carbon Nanotubes
As can be seen in Figures 6.1A amp B, carbon nanotubes may be viewed as a graphite sheet that is rolled up into a nanoscale tube form single-walled carbon nanotubes, SWCNTs FIGURE 6.1. Schematic representation of A single- multi-walled carbon nanotube formation by rolling up graphene sheet s . B carbon nanotube formation based on a 2D graphene sheet of lattice vectors a1 and a2, the roll-up chiral vector Ch na1 ma2, and the chiral angle 0 between Ch and a1. When the graphene sheet is rolled up...
Composition
Detailed knowledge of composition and its distribution within and around QDs is important for a thorough understanding of the QD growth mechanism and of the structure-property relationship of QDs. However, the determination of quantitative composition profiles of QDs is a very challenging task because of the small size of the QDs. As a result, the composition of QDs has been less investigated compared to their shape and size. Most investigations of QD composition suggest that the average...
Strain Effects in Nanostructures Due to Lattice Mismatch in Multi Quantum Wells
In the MBE growth of layered systems the lattice mismatch between barrier and well induces biaxial strains in the interface regions. These strains cause shifts of the LO phonon wavenumber, which are proportional to the strain. For compressive (tensile) strain a blueshift (redshift) of the phonon wavenumber can be observed 43, 115, 137-139 . The amount of this shift may depend on the layer thickness 39, 140, 141 . For ZnSe on GaAs, from the beginning of the epilayer growth large elastic strains...
Periodic Phases 31 MCM41 P6mm
MCM-41 is the simplest and most extensively studied meso-porous silica 4 . In a typical example of synthesis, the alkyltrimethylammonium surfactants, C H2b+1-N(CH3)+X-(X Cl or Br, n 8-10, 12, 14, 16), one of so-called anionic surfactants described as S+I-, were used. According to the simplest picture of the LCT mechanism, these surfactant molecules form micellar rods (Fig. 1a), which further self-assemble into a hexagonal array (Fig. 1b). Silicate ions deposit on the surface of the micellar...
SBA2 P63mmc Fm3m
SBA-2 was first synthesized by Stucky's group in 1995 by using Gemini surfactant C H2 +1N+(CH3)2(CH2)sN+ (CH3)3 (Cn_s_i) 10 . Based on powder XRD results, the material was believed to consist of discrete supercages in a hexagonal close-packed (hcp) arrangement and the space group was determined to be P63 mmc. The unit cell dimensions are a 6 nm and c 10 nm which can be tuned by changing Figure 5. TEM image of 3D porous single crystal of Cr2O3 synthesized using SBA-15 as a template which has...
Crystallography of Titanate Nanotubes
In an early study, Kasuga et al.1 characterized their product as anatase. In a recent paper, the crystal structure of nanotubular titanates was still been RSC Nanoscience amp Nanotechnology No. 12 Titanate and Titania Nanotubes Synthesis, Properties and Applications By Dmitry V. Bavykin and Frank C. Walsh Dmitry V. Bavykin and Frank C. Walsh 2010 Published by the Royal Society of Chemistry, www.rsc.org interpreted as anatase,2 despite the fact that the crystal structure of these nanotubes is...
The Assemblies of NiC and NiO Particle Systems
Powder X-ray diffraction profiles of Fig. 1A clearly show the presence of a majority of fcc Ni, with a small amount of hexagonal Ni3C present from carbon-encapsulated Ni nanoparticles. Additionally, that the hexagonal Ni3C phase is detectable using XRD suggests that the hexagonal Ni3C most likely is one single phase along with majority of fcc Ni phase in these assemblies of Ni C nanoparticles. However, the main reflection peaks of XRD Fig. 1B for pure Ni nanoparticles coated with NiO layers are...
Electron Diffraction Modes And Geometry
Electron optics in a microscope can be configured for different modes of illumination from a parallel beam to convergent beams. Figure 1 illustrates three modes of electron diffraction using different illuminations, 1) selected area electron diffraction (SAED), 2) nano-area electron diffraction (NED) and 3) convergent-beam electron diffraction (CBED). Variations from these three techniques include large-angle CBED 9 , convergent-beam imaging 10 , electron nanodiffraction 11 and their...
Magnetic Micro Nano Bead Based Biochemical Detection System
In the past few years, a large number of microfluidic prototype devices and systems have been developed, specifically for biochemical warfare detection systems and portable diagnostic applications. The BioMEMS team at the University of Cincinnati has been working on the development of a remotely accessible generic microfluidic system for biochemical detection and biomedical analysis, based on the concepts of surface-mountable microfluidic motherboards, sandwich immunoassays, and electrochemical...
Optical Printing
Optical lithography comprises the formation of images with visible or near-UV radiation (A 300-380 nm) in a resist (e.g., Novolac) using shadow or projection printing. Shadow printing may be employed where the gap between mask and wafer is small. In case of projection printing, some sort of image-forming system (e.g., a 4 1 demagnification lens) is interposed between mask and wafer. The linewidth limit of optical printing lies near 0.4 m, although 0.2 m features may eventually be printed under...
Piezoelectric Actuation Mechanism
It is important to mention that the piezoelectric actuation is based on inverse piezoelectric effect, although the piezoelectric detection is based on direct piezoelectric effect. Note a piezoelectric material provides its own internal biasing requirement, either due to absence of a center of symmetry in the case of single-crystal materials such as aluminum nitride (AIN) or zinc oxide (ZnO) or due to a permanent polarization present in ferroelectric materials such lead-zirconate-titanate (PZT)....
Bohrs Model of the Nuclear Atom
The structure of the atom is completely nanophysical, requiring quantum mechanics for its description. Bohr's semi-classical model of the atom was a giant step toward this understanding, and still provides much useful information. By in- Nanophysics and Nanotechnology An Introduction to Modern Concepts in Nanoscience. Second Edition. Edward L. Wolf Copyright 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN 3-527-40651-4 troducing, in 1913, a completely arbitrary quantum number, Bohr 1...
Energy Storage vs Energy Conversion Devices
Although each energy storage and conversion device is characterized by its particular structural and functional dissimilarities, they share common electrochemical foundations. In general terms, we can envisage these devices as electrode pairs in contact with a charge-carrier medium. The negative electrode is called the anode (oxidation reactions take place) where electrons are delivered to the external circuit. The positive electrode is called the cathode, where reduction reactions take place....
Crystal Structure of TiO2
TiO2 exists as three polymorphs, brookite, anatase and rutile. Among these, rutile is the most stable phase. Both the anatase and rutile structures are commonly used in photocatalysis applications. Figure 10.1 illustrates the crystal structures of TiO2 in the form of TiO6 octahedrons. Each octahedron can be considered as one Ti4 cation surrounded by six O2 anions. In rutile, each distorted octahedron is in contact with ten neighbor octahedrons two sharing edge oxygen pairs and eight sharing...
Flatband Potential and Donor Density
Flatband potential is an important parameter in deciding the performance of a semiconductor electrolyte junction towards hydrogen generation. The higher the flatband potential, the greater is the ability of the photoelectrode to split water. The most frequently used method for determination of the flatband potential at a semiconductor electrolyte interface is by Mott Schottky plots. If C is the junction capacitance at electrode potential Vapp, the Mott Schottky equation is given by where eo is...
Excitonic Effects In Quantum Wells
In the case of confined systems for electrons and holes, such as quantum wells, wires, and dots, the excitonic effects are much more important than in bulk solids. In effect, the binding energy of the electron-hole system forming an exciton is much higher in quantum confined systems than in the case of solids, and, therefore, the excitonic transitions can be observed even at temperatures close to room temperature, as opposed to the bulk case for which low temperatures are needed. This makes the...
Living Water and Hydrophobic Interactions
Biomolecules have evolved and flourished in aqueous environments, and basic interactions among biomolecules and their pervasive hosts, water molecules, are extremely important. The properties of intracellular water are controversial. Many authors believe that more than 90 percent of intracellular water is in the bulk phase-water as it exists in the oceans (Cooke and Kuntz, 1974 Schwan and Foster, 1977 Fung and McGaughy, 1979). This traditional view is challenged by others who feel that none of...
Where to Buy Ferrofluids
The science department or the science teacher can order sealed display cells of ferrofluids from Educational Innovations, Inc., at http www.teachersource.com (click on Browse or Search the Catalog , Electricity Magnetism Engines and then Ferrofluids ). A Ferrofluid Experiment Booklet is also available (item FF-150) for about 6. References .HTM READING MATERIAL Karn, Barbara, VickiColvin, Paul Alivasatos, Tina Masciangioli (Eds.). Nanotechnology and the Environment.
The Industrial Structure Giving Rise to Nanotechnology
We don't make the products you use, we make the products you use better. The phrase is a familiar one. We don't make the products you use, we make the products you use better. Although used in commercials by BASF, a company that adds value to existing products with its chemicals and plastics, this phrase could also be used to describe nanotechnology companies. Nanotechnology will serve to improve a number of different types of products in different industries. As we saw in Chapter 1,...
Venture Investment in Nanotechnology
Many nanotech start-ups are not yet ready for venture capital investment. First, despite the enormous resources being dedicated to exploring and engineering at the nanoscale, the field is still in its infancy. Many start-up companies have just recently spun out of breakthroughs in universities and cannot reasonably expect to develop commercial products for at least seven to ten years. Even nanotech companies that can demonstrate functional products lack the ability to scale up for mass...
The Case For Partnering In Nanotechnology
Partnering arrangements are an increasingly common strategy by which companies get products to market. They will be an important consideration for nanotech companies. As one commenter put it, if the 1980s were the Decade of the Merger Acquisition, the 1990s was the Decade of the Strategic Alliance. 3 Indeed, corporate partnerships are a permanent feature of t he business world. 4 The growth of partnerships has been especially strong in emerging technology areas where new companies require help...
Applications of CNT Emitters
The range of potential applications for CNT-based field emission is very large. Any system that uses an electron source could potentially host a CNT field emission device. CNT field emitters are particularly suited when high efficiency is necessary, such as for most space and portable applications, when fast switching or ultrahigh frequency modulation are required and also, when very high current densities are desirable. Several applications for CNT emitters are discussed below. Vacuum...
Variant 1 the cathoderay tube CRT
The cathode-ray tube is the oldest and best known facility for generating moving images. A CRT monitor consists of a vacuum-filled (10-6 to 10-7 torr) glass bulb plus a heated cathode (voltage about 25 kV), also known as the hot cathode or electron gun (Abrams et al. 2003). When heated, the electrons of the negatively charged cathode begin to oscillate and are then emitted from it. Between the cathode and the anode exists an accelerating potential of several kV. Due to this voltage difference,...
DUV and VacuumUV Lithography
Serial processes are time-consuming and therefore not applicable for a cost-efficient and highly productive fabrication of devices with small structures. Therefore, large complexes of structures are transferred together in the size of a chip or larger areas. Such group transfer processes require a high optical precision and highly homogeneous illumination. Again, the wavelength limits the resolution. So a process of continuous stepwise improvement of equipment and technologies ranging from...
Classification and Structure of Doped Fullerenes
Fullerene solids are unique insofar as they can be doped in several different ways, including endohedral doping (where the dopant is inside the fullerene shell), substitutional doping (where the dopant is included in the fullerene shell), and the most commonly practiced exohedral doping (where the dopant is outside or between fullerene shells). Doped fullerenes in the crystalline phase are often called fullerides, in contrast to the term fullerite, which refers to the crystalline phase prior to...
NFMM Characterization of Magnetic Domains
We demonstrate the measurement of electromagnetic properties of magnetic layers in a HD platter by using a NSMM. As the magnetization changed, the intensity of the reflection coefficient Sn varied. The electromagnetic properties of a hard disk were estimated by measuring the microwave reflection coefficient Sn. Figure 5.25A shows the estimated microwave reflection coefficient dependence on the magnetic relative permeability of the CoCrPtTa soft magnetic layer of the HD plater. The inset shows a...
Finite Element Model
Another, perhaps more natural observable in NFMM experiments, is the reflection coefficient Su as a function of frequency from which, of course, the frequency shift can be obtained or Sn as a function of material property for a fixed frequency 20,21 . However, to model Sn is not very straightforward in that one cannot work solely with electrostatics. Furthermore, there are distance scales of very different sizes, for example, the cavity of order centimeters and the tip-sample distance of order...
Biosensing of Fluids by a NFMM
The real-time detection and quantification of concentration of glucose, NaCl and other compounds in fluids with high sensitivity, selectivity, and accuracy is required in many different areas. Accurate and rapid measurement of the glucose concentration is very important in biological analysis and clinical monitoring and in the food processing industry 73-76 . Aqueous NaCl solutions play a fundamental role in many chemical processes in a variety of chemical and biological systems 77,78 . Here,...
Nearfield Interaction
An important strategy for understanding natural and artificial materials is to study the interaction of the material with electromagnetic fields. The properties of metals, semiconductors, and dielectrics at low frequency have been a fruitful area of investigation. The first experiments were transmission experiments done in the far-field region from source, and typically required that the sample size be of the scale of the wavelength 22-26 . In the second generation some experiments were carried...
Vibrational Modes
In this chapter we review the lattice mode structure for the isolated fullerene molecules and for the corresponding molecular solid. Explicit results are given for C60, C70, and higher fullerenes. The effects of doping, photopolymerization, and pressure on the vibrational spectra are reviewed. 11.1. Overview of Mode Classifications Because solid C60 is very nearly an ideal molecular solid, its vibrational modes can be subdivided naturally into two classes intermolecular vibrations (or lattice...
Four Generations of Nano Product Development
In the case of the incorporation of nanomaterials into products, several generations of changes to manufacturing can be anticipated . Current products in the marketplace today typically fall into the 1st generation, where relatively minor modifications to existing processing equipment were needed to incorporate nanomaterials into the product For example, surface coatings of nanofibers and nanowhiskers have been used for improved filtration and for the nano-pants fabric made by Nano-Tex 3 . More...
Silica Based Porous Materials
A wide variety of different porous materials are known. Following the classification by IUPAC, they can be grouped by the size of their pores microporous solids with pore diameters up to 2 nm with zeolites and metal-organic frameworks (so-called MOF structures) as the most prominent representatives, mesoporous solids with pore sizes between 2 and 50 nm, e.g. aerogels, pillared clays, or M41S phases, and macroporous solids with pore sizes larger than 50 nm, such as foams or glasses. In addition,...
Physical Properties Of Micelles
Again, the common aspects of the self-assembly of surfactant (and amphiphilic polymer) systems are that it is a thermodynamic, random, and nonhierarchical process with molecular-length scale. This section provides details on this issue. The definitions of three important parameters for micelles also will be given critical micelle concentration (cmc), aggregation number (n), and degree of counterion binding on the surface of micelles (a) (Tanford, 1980 Zana, 1991 Nagarajan and Ruckenstein, 2000...
Atomic and Molecular Basis of Nanotechnology
The molecular theory of matter starts with quantum mechanics and statistical mechanics. According to the quantum mechanical Heisenberg Uncertainty Principle the position and momentum of an object cannot simultaneously and precisely be determined 8 . Then the first question that may come into mind is, how could one be able to brush aside the Heisenberg Uncertainty Principle, Figure 2, to work at the atomic and molecular level, atom by atom as is the basis of nanotechnology. The Heisenberg...
Coacervation Phase Separation
Coacervation-phase separation is a method to use a coacervation-inducing agent to reach the coacervation-phase separation during after the solvent evaporation to form the microcapsules or the nanocapsules. The coating can be controlled by changing the parameters during the process, so that the drug content, particle size distribution, biomedical properties, etc. of the microcapsules nanocapsules can be controlled. This procedure has been employed widely for preparation of microcapsules...
The Vibrating Uniform Lattice
The elastic, spring-like nature of the interatomic bonds, together with the massive atoms placed at regular intervals these are the items we isolate for a model of the classical mechanical dynamics of the crystal lattice see Box 2.3 for brief details on Lagrangian and Hamiltonian mechanics . Here we see that the regular lattice displays unique new features unseen elsewhere acoustic dispersion is complex and anisotropic, acoustic energy is quantized, and the quanta, called phonons, act like...
Absorption and Emission Spectroscopy of Carbon Nanotubes
Compared to the vibrational spectroscopy of carbon nanotubes, their absorption and luminescence spectroscopy kind of lives in the shadows. This is, however, not due to a lack of information these methods could provide to the understanding of the nanotubes' electronic structure. There are rather experimental complications that arise from the inhomogeneity of the available materials. These methods could especially elucidate the structure of bands farther distant from the Fermi level. Due to the...
Microtubule Organizing Centers MTOC and Centrioles
MTOC and their chief components, centrioles, are the specific apparatus within living cells which trigger and guide reorganization of cytoplasm such as occurs during growth, generation of form and function (differentiation) and cell movement. The enigmatic MTOC determine where, when, and how these functions occur (Figure 5.11). MTOC (or centrosomes) contain centrioles and pericentriolar substance which facilitates tubulin assembly by somehow lowering Cc. Centrioles are the common structure in...
Ion Beam Lithography
In analogy with the use of electrons, ions can also be applied for lithography 91 . They too can be generated as well as accelerated by the electrode arrangements, filtered according to their energy and locally guided by electronic optics. Ion beams are utilized in four directions of nanolithography - to fabricate structures in ion-beam-sensitive resists - for structure transfer from structured resist layers in functional layer by ion beam etching - to structure directly by local etching using...
Holographic datastorage system HDSS
The late twentieth century had some pretty fancy dreams. For example, the 1978 movie Superman flew fantastic special effects at audiences faster than a speeding bullet including a glowing green crystal (a gift from Superman's alien father) that created the Fortress of Solitude at the North Pole complete with a data-retrieval system that housed the entire history of Superman's home planet and all the engineering smarts needed to create that crystal palace. (Automatically, at that.) Impressive as...
Single Electron Tunneling in Semiconductor Structures
In this section, we focus on two QD structures that are commonly used in the study of single-electron phenomena. One is the lateral QD shown in Figure 1a. Metal electrodes are Copyright 2004 by American Scientific Publishers All rights of reproduction in any form reserved. Encyclopedia of Nanoscience and Nanotechnology Edited by H. S. Nalwa Volume 9 Pages (105-129) Figure 1. (a) Schematic of a lateral QD. Negatively biased metal electrodes patterned on the surface of a 2DEG heterostructure of...