Chemical Vapor Deposition
Chemical vapor deposition CVD may be defined as the deposition of a solid on a heated surface from a chemical reaction in the vapor phase. It is a versatile process suitable for the manufacturing of coatings, powders, fibers, and monolithic components. It is possible to produce most metals, metal oxides, and non-metallic elements such as carbon and silicon as a large number of compounds including carbides, nitrides, oxides, intermetallics, and many others. The main advantage of CVD is that the...
Fouling and Nanofiltration Performance
Most municipal, industrial, and natural waters contain complex mixtures of dissolved, macromolecular colloidal, and particulate matter. Conventional processes used to pretreat NF feed waters fail to remove submicron colloids, macromolecules and dissolved matter. This matter accumulates at the membrane surface and results in severe performance decline a phenomenon known as fouling. Fouling of NF membranes may result in loss of both solvent flux and solute retention. A review of fouling studies...
Info Rib
on the web http www.intel.com research silicon moorespaper.pdf accessed September 2002 . 10. Intel press release http www.intel.com pressroom 28. archive releases 20011017man.htm accessed September 2002 . 11. Intel press release http www.intel.com pressroom archive releases 20020813tech.htm accessed Septem- 29. ber 2002 . 12. International Technology Roadmap for Semiconductors web pages http public.itrs.net Files 2001ITRS 30. PIDS.pdf accessed September 2002 . 13. Wang, K.L. Issues of...
References Oni
1. Liu, J. Alvarez, J. Kaifer, A.E. Metal nanoparticles with a knack for molecular recognition. Adv. Mater. 2000, 12, 1381-1383. 2. Storhoff, J.J. Mirkin, C.A. Programmed materials synthesis with DNA. Chem. Rev. 1999, 99, 1849-1862. 3. Templeton, A.C. Wuelfing, W.P. Murray, R.W. Monolayer-protected cluster molecules. Acc. Chem. Res. 2000, 33, 27-36. 4. Brust, M. Walker, M. Bethell, D. Schiffrin, D.J. Whyman, R. Synthesis of thiol-derivatized gold nano-particles in a two-phase liquid-liquid...
References Hus
1. Brust, M. Fink, J. Bethell, D. Schiffrin, D.J. Keily, C. Synthesis and reactions of functionalized gold nanopar-ticles. J. Chem. Soc., Chem. Commun. 1995, 1655-1656. 2. Brust, M. Walker, M. Bethell, D. Schiffrin, D.J. Whyman, R. Synthesis of thiolo-derivatized fold nano-particles in a two-phase liquid-liquid system. J. Chem. Soc., Chem. Commun. 1994, 801-802. 3. Templeton, A.C. Wuelfing, W.P. Murray, R.W. Monolayer-protected cluster molecules. Acc. Chem. Res. 2000, 33, 27-36. 4. Whetten,...
References Ccb
1. Fabregat-Santiago, F. Mora-Ser , I. Garcia-Belmonte, G. Bisquert, J. Cyclic voltammetry studies of nanopor-ous semiconductors capacitive and reactive properties of nanocrystalline TiO2 electrodes in aqueous electrolyte. J. Phys. Chem. B 2003, 107 3 , 758-768. 2. Rothschild, A. Komem, Y. On the relationship between the grain size and gas-sensitivity of chemo-resistive metal-oxide gas sensors with nanosized grains. J. Elec-troceram. 2004, 13, 697-701. 3. Vinodgopal, K. Kamat, P.V. Enhanced...
Chemical Methods
The most potential and successful route for preparing homogeneous ceramic materials is liquid phase chemistry. The most widely used and perhaps most reliable method is the sol-gel method. There are many other wet chemistry methods known, such as microemulsion techniques and precipitation from solutions. Another novel technique is the mechanochemical synthesis method, which involves solid-state chemistry reactions. The synthesis of MMOs by sol-gel technique is one of several liquid phase methods...
Electrochemical Properties
Furthermore, the aforementioned characteristics are the primary factors that deprive the overall performance of the battery, which include the following Inferior electrochemical stability. Inferior mechanical properties. Poor thermal management capabilities. Inferior manufacturability. Potential hazards, especially of the liquid electrolytes, because of leakage, deposition, and explosion. To obviate the aforementioned deficiencies associated with cathode materials, researchers have developed a...
The Assemblies of FeC and FeO Particle Systems
Powder X-ray diffraction patterns of both Fe C and Fe O nanoparticles are shown in Fig. 8A and B, respectively. It is very apparent to reveal that a-Fe bcc , g-Fe fcc , and Fe3C orthorhombic nanophases are detected from the assemblies of Fe C nanoparticles these three phases are usually found in similarly prepared Fe-C nanocomposites. 19 However, dominant a-Fe nanophases and a small amount of Fe3O4 phases are examined from the assemblies of Fe O nanoparticles. As revealed by high-resolution...
Electron Beam Lithography
Electron beam lithography in which a beam of electrons, rather than photons, is used as the exposure source has extremely high-resolution capabilities combined with a large depth of focus. To date, it has been mainly used in the production of masks and reticules for optical lithography. But it has also been used in the fabrication of very fine-scale devices for fundamental and device-verification studies, and also in the small-scale production of the specialized very high frequency devices....
Info Gdr
Fig. 5 the viscosity is low even in the undercooled regime, but increases sharply upon approaching the glass transition. It appears that the marginal glass-forming alloys exhibit a fragile type of viscosity behavior. It is evident that the transport behavior will impact both the ease of glass formation and the kinetics of nanocrystal development. The different synthesis routes that are shown in Fig. 4 originate from the relative time scales for the onset of nucleation and melt cooling. The...
References Fgd
1. Breck, D.W. Zeolite Molecular Sieves Wiley New York, 1974. 2. Davis, M.E. New vistas in zeolite and molecular sieve catalysis. Acc. Chem. Res. 1993, 26, 111-115. 3. Camblor, M.A. Corma, A. Mifsud, A. Perez-Pariente, J. Valencia, S. Synthesis of nanocrystalline zeolite beta in the absence of alkali metal cations. In Studies in Surface Science and Catalysis Chon, H., Ihm, S.-K., Uh, Y.S., Eds. Elsevier Amsterdam, 1997 Vol. 105, 341-348. 4. Castagnola, N.B. Dutta, P.K. Spectroscopic studies of...
Info Sbv
2800 2900 3000 3100 Wavenumber cm1 Fig. 7 Sum frequency generation spectra collected from the PBMA d-PS interface lower left panel and the PBMA PS interface lower right panel . Both ssp and sps spectra collected from the two interfaces are shown. The upper panel shows the experimental geometry. Research has also been conducted on the structure of the PS PMMA interface using SFG, showing ordered ester methyl groups at the inter-face. 18 Sum frequency generation studies on the acetate Comb PS...
Surface Chemistry Of Aluminum Oxide Nanoparticles
Because of its importance as a catalyst, the surface chemistry of aluminum oxide, Al2O3, has been extensively studied over the years. 5,6,13-16 In many of these studies, bulk non-nanocrystalline Al2O3 has been studied. 13-16 More recent work has been done on the surface chemistry of nanocrystalline NC -Al2O3. 5,6,11-17 Carnes 17 has reported a method similar to the preparation of AP-MgO for the preparation of NC-Al2O3. This again involves aerogel preparation as it did with AP-MgO. 17 These...
Info Rly
charged either negatively at high pHs or positively at low pHs. For metal oxides and hydroxides see Eq. 1 below positive surface neutral surface ' negative surface where M represents a metal cation at the surface. For coal representing a typical hydrophobic miner-alwhere R represents a hydrocarbon compound constituting the coal structure see Eq. 2 below . F negative surface neutral surface ' positive surface Consequently, for simple metal oxides and hydroxides, e.g., SiO2, Al2O3, Fe2O3, and...
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...
References Sfr
1. Kish, L.B. End of Moore's law thermal noise death of integration in micro and nanoelectronics. Phys. Lett. 2002, 305, 144-149. 2. Huang, B. Qin, J. Walters, J. Bernstein, J.B. Development of Derating Guidelines for Semiconductor Devices. In Aerospace Vehicle Systems Institute Report 2003 unpublished. 3. Kim, J. Kish, L.B. Can Single Electronic Microprocessors Ever Work at Room Temperature In Proceedings of SPIE, Vol. 5115, Conference on Noise in Nanoelectro-nics, Sensors and Standards, Santa...
SYNTHESIS OF SEMICONDUCTOR NPs IN THE APOFERRITIN CAVITY
Reports of inorganic NP synthesis in the apoferritin cavity have so far mostly been of metal complexes. It is of great interest to explore the possibility of synthesizing compound semiconductor NPs in the apoferritin cavity. Because the electron energy levels of the semiconductor NPs depend on their size and shape, semiconductor NPs can be a quantum dot or photofluorescence marker and are very attractive for nanoelectronics. However, the introduction of oppositely charged ions is very difficult...
Mechanical Synthesis
Mechanical synthesis as a method for producing nano-powders may be divided into two categories mechanical milling and mechanical alloying. Mechanical milling is used both for grinding and amorphization of the starting material. Mechanical alloying requires grinding, mixing, mass transfer, and chemical interaction of powders of several pure elements, compounds, or alloys. Substances in the crystalline and amorphous states may be prepared by mechanical alloying. Mechanical synthesis is the most...
Nanocrystallization During Melt Quenching
As noted in Fig. 4, it is possible to encounter conditions that represent the maximum nucleation rate i.e., the minimum time for the onset of nucleation or the nose of the C curve during continuous cooling. One important requirement to achieve a maximum nucleation density is the removal of potent heterogeneous nucleation sites so that the alloy melt may be cooled to the temperature yielding the maximum nucleation rate without prior crystal formation. For homogeneous nucleation the temperature...
S Ear
Fig. 7 Field-emission scanning electron microscope FESEM images of two commercially available nanofiltration membranes with RMS roughness values of A 12.8 nm and B 56.5 nm taken from Ref. 43 . Additional A and B membrane properties include zeta potentials of 18 and 25mV at 10mM and pH 7 , pure water contact angles of 51.9 and 51.7, hydraulic resistances of 3.26 x 1010 and 3.13 x 1010Pa s m, and salt rejections of 35 and 83 at 30 gallons per square foot of membrane per day, gfd, and 10 mM NaCl ,...
Defining NF Separation Performance
When an external pressure is imposed on a liquid adjacent to a nanofiltration membrane, the liquid will flow through the membrane in proportion to the applied pressure. Liquid flow through a NF membrane is described as a solvent flux Jv , which is given by a Darcy-type relation such as in which Apeff is the effective trans-membrane pressure, m is the permeate viscosity, and Rtot is the total hydraulic resistance toward solvent flow. Dissolved solutes also flow toward the membrane by the...
C3
Fig. 1 A and B SEM images illustrating the morphology of melt-spun and ground Pr2Fe14B a-Fe particles, and C and D BF and DF TEM images showing the nanocrystalline 25-30 nm grain size of the starting powders. Fig. 1 A and B SEM images illustrating the morphology of melt-spun and ground Pr2Fe14B a-Fe particles, and C and D BF and DF TEM images showing the nanocrystalline 25-30 nm grain size of the starting powders. Fig. 2 A Schematic illustration of three-capsule plate-impact fixture used for...
Reduced brittleness and enhanced ductility and superplasticity
Superplasticity and ductility refer to the capability of some polycrystalline materials to undergo extensive tensile deformation without necking or fracture. Ceramic brittleness is the biggest technical barrier in practical applications, especially in load-bearing applications. Theoretical and experimental results provide evidence for the possibility that traditional brittle materials can be ductilized by reducing their grain sizes. 1 When made from nanoparticles, brittle ceramics can be...
Microwave Synthesis
Recently, there has been a growing interest in heating and sintering of ceramics by the microwave energy. 48,49 The interest in the use of microwave processing spans a number of fields from food processing to medical applications to chemical applications. A major area of research in microwave processing of ceramics includes microwave material interaction, dielectric measurement, microwave equipment design, new material development, sintering, joining, and modeling. Therefore the microwave...
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...
M Foy
Fig. 12 Cyclic hardening softening curves of some selected SPD metals with UFG structures. Source From Ref. 33 . Softening is common for cyclic deformation of pre-strained f.c.c. metals. 4,5,51 It has been also clearly observed in many ECAP f.c.c. metals such as cop-perPo-22,26 Ni, 29 single-phase Al-Mg 5056 3031 and Fe-36Ni Invar alloys, 32 and precipitation-hardened Cu0.44Cr0.2Zr alloy. 36 However, the detailed characteristics of cyclic softening, its phenomenology, and microscopic mechanisms...
References Lxb
1. Faraday, M. Experimental relations of gold and other metals to light. Philos. Trans. R. Soc. London 1857, 147, 145. 2. Berry, C.R. Structure and optical absorption of Agl microcrystals. Phys. Rev. 1967, 161, 848. 3. Brus, L.E. Electron-electron and electron-hole interactions in small semiconductor crystallites the size dependence of the lowest excited electronic state. J. Chem. Phys. 1984, 80, 4403. 4. Rao, C.N.R. Kulkarni, G.U. Thomas, P.J. Edwards, P.P. Size-dependent chemistry properties...
Motor Proteins In A Synthetic Environment
Controlling the interaction between the motor proteins and the synthetic materials is a major challenge in the A fundamental element in the engineering of biomole-cular motor-powered devices and materials is the ability to modulate the activity of the motors. To date, two strategies have been used to regulate the functionality of biomolecular motors in synthetic systems. The first strategy involved the controlled release of caged ATP into solution to modulate the linear translation of...
S Ues
Murata, M. Yamada, M. Fujita, T. Kojima, K. 72. Kurihara, M. Kubo, K. Kobayashi, Y. Nishihara, H. Structural conversion and spin separation in bis fer-rocenylethynyl anthraquinones triggered by protoncoupled intramolecular electron transfer. J. Am. Chem. 73. Soc. 2001, 123, 12903. Bakkers, E. Marsman, A. Jenneskens, L. Vanmaekelbergh, D. Distance-dependent electron transfer in Au spacer Q-CdSe assemblies. Angew. Chem., Int. Ed. Engl. 2000, 39, 2297. 74. Pethkar, S. Aslam, M. Mulla, I. Ganeshan,...
Cyclic Softening and Hardening
Fig. 10 Basic cyclic stress-strain curves for several UFG ECAP metals. Fig. 10 Basic cyclic stress-strain curves for several UFG ECAP metals. Fe-36 Ni Invar alloy subjected to different number of ECA pressings between 2 and 12 are approximately the same, i.e., the cyclic strain hardening exponent nb' values are nearly equal for all samples regardless of the preimposed strain. Fig. 11 compares the monotonic and CSSC for ECAP Fe-36 Ni Invar alloy only the initial part of the tensile stress-strain...
Nanoparticle Sensors
The optical and or electrical electrochemical properties of metallic or semiconducting nanoparticles and Fig. 4 Schematic representation of a self-assembling, hydrogen-bonding ferrocene amide capable of electroanalytical anion sensing. With the specific receptors shown, hydrogen phosphate anion recognition cathodic shifts in the ferrocene half-wave potential are gt 290 mV in magnitude greater, to our knowledge, than anything reported to date. Source From Ref. 81 . Fig. 4 Schematic...
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Preparation of a homogeneous solution of pure precursor in an organic solvent, which is miscible with water or the hydrolysis reagent. Preparation of sol from solution by treating the homogeneous solution with H2O, or H2O with HCl NaOH NH4OH. Allowing the sol to convert into gel by polymerization aging . Fig. 1 Steps involved in sol-gel method. Fig. 1 Steps involved in sol-gel method. 4. Shaping of gel into the desired form or shape followed by drying. In this step, solvent is removed. The...
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Fig. 6 This figure shows a cyclic receptor 2 , with an ada-mantanyltrimethylammonium cation included in its internal cavity. Fig. 6 This figure shows a cyclic receptor 2 , with an ada-mantanyltrimethylammonium cation included in its internal cavity. ous examples of and additional details concerning organic receptor molecules that have been studied in solution may be found in a review by Ma and Dougherty Fig. 6 . 20
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3. Segal, V.M. Materials processing by simple shear. Mater. Sci. Eng., A 1995, 197, 157-164. 4. Suresh, S. Fatigue of Materials Cambridge University Press Cambridge, United Kingdom, 1991. 5. Polak, J. Cyclic Plasticity and Low Cycle Fatigue Life of Metals Elsevier The Netherlands, 1991. 6. Valiev, R.Z. Materials science nanomaterial advantage. Nature 2002, 419, 887-889. 7. McFadden, S.X. Mishra, R.S. Valiev, R.Z. Zhilyaev, A.P. Mukherjee, A.K. Low-temperature superplasticity in nanostructured...
Exchangecoupled Nanocomposite Permanent Magnets
One of the most important properties of permanent magnets is the maximum energy product, BH max, which is a measure of the maximum stored energy. In the last 50 years, 1,2 remarkable evolutionary and revolutionary progress made in permanent magnet materials has resulted in the development of AlNiCo's with BH max 8 MGOe, strong rare earth SmCo5 1 5 and Sm Co, Fe, Cu, and Zr z 2 17 with BH max 30 MGOe, and the new R-Fe-B supermagnets, which have large values of magnetization and...
Gmr Head Definition
In 1988, a new magnetoresistive effect was discovered in Germany and France, identified as the giant magne-toresistive GMR effect, using multifilms of chromium and iron synthesized by molecular beam epitaxy. When this Cr Fe structure was tested at liquid helium, cryogenic temperatures in very strong magnetic fields of several thousand Oersteds, or about 100 times greater than what would be obtained from a rotating magnetic media in a disk drive, the result was a resistance change of as much as...
GouyChapman diffuse doublelayer model
This is independently known as the Gouy-Chapman model. They expressed that, in addition to the electrostatic attraction of counterions to the charged surface, some of them tend to diffuse toward the bulk solution because of their thermal motion. Note that the EDL theory can be developed for different solid geometries such as flat plate, sphere, and cylinder. Because most studies for organic and inorganic solids in liquids assume the flat plate geometry, 17,18 here we also consider the flat...
References
1. Binnig, G. Quate, C.F. Gerber, C. Atomic force microscope. Phys. Rev. Lett. 1986, 56, 930-933. 2. Mate, C.M. McClelland, G.M. Erlandsson, R. Chiang, S. Atomic-scale friction of a tungsten tip on a graphite surface. Phys. Rev. Lett. 1987, 59, 1942-1945. 3. Burnham, N.A. Colton, R.J. Measuring the nano-mechanical properties and surface forces of materials using an atomic force microscope. J. Vac. Sci. Tech-nol., A, Vac. Surf. Films 1989, 7, 2906-2913. 4. Nyffenegger, R.M. Penner, R.M....
Methods Of Zeta Potential Measurements
Electrokinetic measurements using electrophoresis, electroosmosis, streaming potential, and sedimentation potential can be interpreted to yield a quantity known zeta or electrokinetic potential. 3,42 Of these four techniques, the electrophoresis is perhaps the best known and most commonly used technique to measure the zp of minerals. While the electrophoresis technique with modifications is extended for the measurement of very fine particles such as nanoparticles lt 100nm and colloidal...
Preconcentration For Analytical Applications
What we know is typically bound by what we can confidently measure. Consequently, there are ongoing efforts to improve the sensitivity, selectivity, and speed of analytical methods. One approach to improving any analytical method is to separate the analtye s for the sample matrix and concentrate them into a smaller volume prior to measurement. When this preconcen-tration is carried out with small quantities of sorbents, the method is typically referred to as a solid-phase microextraction SPME ....
Introduction Wdn
In many aspects, colloidal particles suspended in a liquid behave like large idealized atoms that exhibit liquid, glass, and crystal phases similar to those observed in atomic systems. 1-6 Phase transitions in colloidal systems have been intensively studied over the last decade not only because of the theoretical interest for addressing fundamental questions about the nature of liquids, crystals, and glasses, but also for many practical applications of colloids. 7-11 In recent years, colloidal...