bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the Pull-In Voltage for MEMS Parallel Plate Capacitor Actuators
Authors: Saucedo-Flores Emmanuel , Ruelas Rubén , Flores Martín , Chiao Jung-chih 
Published: April 2011

ABSTRACTThis paper provides new investigation for the static and dynamic behavior of a MEMS parallel plate capacitor derived by analytical and numerical design modeling programs developed in Matlab. One significant finding is about the role, which has so far overlooked in many analyses, of a dielectric layer normally placed on top of the ground electrode to avoid short circuiting risks. It is demonstrated in this paper that this layer produces an increased force between electrodes that in turns decreases the well-known pull-in voltage, Vpi, as compared to the one calculated when this dielectric layer is not considered on the system's static analysis. Expressions for the static Vpi and its corresponding maximum stable electrode swing xpi are derived to take the above effect into account.The system dynamic analysis is done with a user-friendly Simulink interface constructed to allow easy introduction of capacitor design dimensions, material parameter values and voltage signal stimuli. The impact of any combination of these parameters on the electro-mechanical system behavior, that is, the voltage-electrode position dependence data can be easily extracted and become of help for design decision making on the early design stages of this type of structures. This modeling tool interface is based on solving the full differential equation that describes the free electrode displacement without relying on linearizing the inverse quadratic electrode separation dependence of the electro-static force term. This approach intrinsically takes into account the voltage dependant k-spring softening effect derived precisely from a linearizing simplification. Finally, by applying a saw-tooth voltage waveform, the dynamic pull-in voltage and the maximum stable electrode travel range are observed to go well beyond the predicted static pull-in voltage and travel range values.
Metastable Phase Formation and Stimulated Transitions in Metallic Nanometer Films
Authors: Meyer Dirk C. , Levin Alexandr A. , Braun Stefan , Gorbunov Andre , Mertig Michael , Pompe Wolfgang , Paufler Peter 
Published: April 2011

ABSTRACTDue to the non-equilibrium nature of deposition techniques, thin films can exhibit an energetic state far from thermodynamic equilibrium. Energy supply can stimulate a transition into other metastable states. Examples of metastable phase formation presented in this work are thermally stimulated solid state reactions in metallic nanometer Al/Co/Ni multilayers and phase formation and transition in metallic alloy films of the elemental materials system Fe-Cr. An interesting application illustrates the technical potential of metastable nanometer films.
Spin-Dependent STM Tunnelling Study of the Patterned Magnetite (111) Surface
Authors: Berdunov N. , Murphy S. , Mariotto G. , Shvets I. V. 
Published: April 2011

ABSTRACTUnder oxidizing preparation conditions the magnetite (111) surface reconstructs to a highly ordered superlattice. This surface reconstruction represents an oxygen-termination of the magnetite bulk. We employ spin-polarized (SP) STM to study the spin-dependent tunnelling between a magnetite (111) sample and an antiferromagnetic tip through a vacuum barrier. Atomic scale STM images show significant magnetic contrast corresponding to variations in the local surface states induced by oxygen vacancies. The local variations of the tunnelling magnetoresistance around these vacancies correspond to 150%. By employing SP-STM measurements and First principles calculations we could conclude that an oxygen top-layer considerably changes the SP properties of the magnetite surface. We explain the appearance of the superstructure in terms of electron-lattice instability due to the surface strain.
A Thermodynamic Approach in Tuning Phase Stability in Nanocomposite Multilayers
Authors: Thompson G. B. , Banerjee R. , Fraser H. L. 
Published: April 2011

ABSTRACTChanges in the crystallographic phase stability of individual layers in a multilayered thin film stack are expected to have a significant influence upon the functional properties of the structure. The ability to predict and tune these phase stability states is of relevant importance in order to maximize the functional properties of the multilayer. A classical thermodynamic methodology, based upon competitive volumetric and interfacial free energies, has been used in the prediction and subsequent confirmation of the hcp to bcc phase stability in a Ti/Nb multilayer. An outcome of this model is a new type of phase stability diagram that can be used to predict the hcp Ti and bcc Ti phase stability as a function of length scale and volume fraction. The Ti layers were subsequently alloyed with a bcc-stabilizing element. The alloyed sputtered deposited Ti layers were able to stabilize the bcc Ti phase to a larger layer thickness as compared to the unalloyed Ti/Nb multilayers. The percentage of alloying element added to the Ti layer in controlling the critical transition thickness between the two phase states had good agreement with the predictions proposed by the thermodynamic model.
Low Potential Stable Glucose Detection at Carbon Nanotube Modified Gold Electrodes
Authors: Wang S. G. , Zhang Qing , Wang Ruili , Yang D. J. , Yoon S. F. , Zhang R. 
Published: April 2011

ABSTRACTThe subtle electronic properties and large electroactive surface of carbon nanotubes (CNTs) suggest that they have the ability to promote electron-transfer and favor electrocatalytic behavior in electrochemical reactions when they are employed as an electrode. In this paper, CNT-modified gold electrodes for glucose biosensor have been fabricated using multi-walled carbon nanotubes. The CNT-based electrode exhibits a strong and stable amperometric response toward glucose even at a low potential of +0.35 V versus Ag/AgCl in comparison with the glassy carbon-based electrode.
Effects of DC and AC Magnetic Fields on Grain Growth in Electrodeposited Nanocrystalline Nickel
Authors: Matsuzaki T. , Yamada T. , Jyuami K. , Tsurekawa S. , Watanabe T. , Palumbo G. 
Published: April 2011

ABSTRACTThe effects of DC and AC magnetic fields on grain growth in electrodeposited nanocrystalline nickel were studied. Magnetic annealing was conducted at 573K in the ferromagnetic temperature region and at 693K in the paramagnetic temperature region. Both DC and AC magnetic annealing could enhance the grain growth and produced a homogeneous grain structure at 573K. On the other hand, AC magnetic annealing shortened the incubation time for the late stage abnormal grain growth at 693K in the paramagnetic temperature region, while DC magnetic field could not affect the incubation time.
Macroporous Morphology Induced by Phase Separation in Sol-Gel Systems Derived from Titania Colloid
Authors: Konishi Junko , Fujita Koji , Nakanishi Kazuki , Hirao Kazuyuki 
Published: April 2011

ABSTRACTMacroporous titania gels have been prepared by the sol-gel method starting from aqueous colloidal dispersion of titania. The use of titania sol instead of highly reactive titanium alkoxide allows us to control the rate of gelation. Macroporous morphology is formed when the transitional structure of phase separation is fixed as permanent structures by the sol-gel transition. The domain size can be controlled reproducibly by changing the starting composition. The crystal structure of the titania gel is transformed from anatase to rutile through the heat treatment at 900°C, while the macroporous morphology remains unchanged.
Contact Compression of Self-assembled Nano- and Micro-scale Pyramid Structures on Au (100) Surface
Authors: Wang J. , Ward D. , Curtin W. A. , Kim K.-S. 
Published: April 2011

ABSTRACTA process of self-assembly induced by electro-chemical etching was used to produce nano and micrometer scale pyramid-structures on (100) surfaces of gold. The pyramids grew in a self-similar fashion with the facets aligned in (114) plane. Using the unique characteristics of the self-similar pyramid structure, plastic compression of the pyramids by a flat-surface platen was performed to study length scale effects in the plastic deformation. A continuum limit analysis and a finite element simulation as well as molecular dynamics simulations were carried out to predict the deformation and load-displacement behavior of the pyramid compression. The limit analysis predicts that the load of compression is proportional to the square of the contact-compression displacement. The continuum analysis provides estimation on the asymptotic behavior of the elastic-plastic load-deflection response of the pyramid under compression for a large value of displacement. The three dimensional molecular dynamics simulation was utilized to study the dislocation activities during the early stage of the pyramid compression. Experiments were also carried out by pressing the pyramids with an atomically flat mica surface. The deformation of the compressed pyramid was measured using an Atomic Force Microscope (AFM). The continuum analyses predict size independent values of the slope change of the pyramid facets near the contact edge, caused by plastic deformation. However, atomistic simulation predicts an opposite value of the slope change to the prediction of the continuum analyses. The AFM measurements of the slope change show size dependent transition from the prediction of the continuum analyses to that of the atomistic simulations. The transition data provide an apparent characteristic length of the size dependence of plastic deformation in a small volume. Molecular dynamics show that at very small length scale the size effect is strongly influenced by surface adhesion effects.
Nanocomposites of Liquid Crystalline Polyhedral Oligomeric Silsesquioxane Particles and Liquid Crystalline Polymers
Authors: Somlai Alline P. , Iyer Subramanian , Schiraldi David A. 
Published: April 2011

ABSTRACTA new liquid crystalline nanoparticle has been synthesized by the reaction of a cyanobiphenyl derivative with polyhedral oligomeric silsesquioxane (POSS®*). Two POSS nanoparticles, liquid crystalline POSS (LC POSS 3) and a non-LC isooctyl POSS (OPOSS), were then compounded at 2.5 wt % into thermotropic polyester liquid crystalline polymers (LCPs) poly(hexamethylene 4,4'-bibenzoate), poly(diethylene glycol 4,4'-bibenzoate) as well as a frustrated LCP 45:55 poly(ethylene terephthalate-co-4,4'-bibenzoate). These polymers are currently being studied for potential use in high performance fibers and high barrier packaging materials. A comprehensive study of LCP/LC POSS 3 nanocomposites will focus on any changes in the thermal and mechanical properties of the LCPs with increasing LC POSS 3 concentration. It will be determined how incorporation of LC POSS 3 affects the liquid crystalline phases of an amorphous and crystalline LCP. Of special interest is the incorporation of LC POSS 3 into a frustrated LCP. It is proposed that the LC POSS 3 might help to unfrustrate the LCP.
Controlled Hierarchical Pore Structures in Ethylene-Bridged Polysilsesquioxane Gels
Authors: Kobayashi Yuki , Nakanishi Kazuki , Hirao Kazuyuki 
Published: April 2011

ABSTRACTFormation of hierarchical macropores and mesopores in ethylene-bridged polysilsesquioxane sol-gel systems via concurrent sol-gel transition and phase separation induced by the incorporation of supramolecular templats has been investigated. A series of poly(ethylene-glycol)-poly(propyleneglycol)- poly(ethyleneglycol) triblock copolymers, EOPOEOs, have been employed as supramolecular templates, while 1,2-bis(trimethoxysilyl)ethane was used as a polysilsesquioxane source. Successful combination of templated mesopores and well-defined macropores due to phase-separation has been found in the system with EOPOEOs having 70 PO units and respective 20 EO units. Although similar macroporous morphology has been obtained for all the EOPOEOs with EO chain longer or shorter than 20 units, the optimum composition for the co-continuous macropores and that for templated mesopores deviated from each other, resulting in the failure of producing hierarchical macropores and mesopores.
Characterization and Applications of Modulated Optical Nanoprobes (MOONs)
Authors: Anker Jeffrey N. , Behrend Caleb J. , McNaughton Brandon H. , Roberts Teresa Gail , Brasuel Murphy , Philbert Martin A. , Kopelman Raoul 
Published: April 2011

ABSTRACTModulated optical nanoprobes (MOONs) are microscopic (spherical and aspherical) particles designed to emit different fluxes of light in a manner that depends on particle orientation. When particle orientation is controlled remotely using magnetic fields (MagMOONs) it allows modulation of fluorescence intensity in any selected pattern including square and sinusoidal waves. The broad range of sizes over which MOONs can be prepared allows them to be tailored to applications from intracellular sensors using submicron MOONs to immunoassays using larger MOONs (1–10μm). In the absence of external fields, or material that responds to external fields, the particles tumble erratically due to Brownian thermal forces. These erratic changes in orientation cause the MOONs to blink. The temporal pattern of blinking contains information about the local rheological environment and any forces and torques acting on the MOONs.
Phase Separation of a Binary Liquid System in Controlled-Pore Glass
Authors: Schemmel S. , Akcakayiran D. , Rother G. , Brulet A. , Farago B. , Hellweg Th. , Findenegg G.H. 
Published: April 2011

ABSTRACTThe phase separation behaviour and the dynamics of concentration fluctuations of binary liquid mixtures are strongly influenced by confinement effects. We have investigated this confinement effect for the binary system isobutyric acid iBA + D2O imbibed into a mesoporous silica glass (CPG-10). The dynamics of the mixture are studied in the one-phase region as well as in the phase-separated state by means of neutron spin echo spectroscopy (NSE). Moreover, the averaged structures of the liquid are explored by means of small angle neutron scattering (SANS) leading to a length scale 4 < ξ < 9 nm for the fluctuations. The associated effective diffusion coefficient Deff as obtained for NSE is found to decrease with temperature ny nearly one order of magnitude in the temperature range from 75°C to 25°C.
Single Stranded dna Translocation Through a Fluctuating Nanopore
Authors: Flomenbom O. , Klafter J. 
Published: April 2011

ABSTRACTWe investigate the translocation of a single stranded DNA (ssDNA) through a pore, which fluctuates between two conformations, by using coupled master equations (ME). The probability density function (PDF) of the first passage times (FPT) of the translocation process is calculated, displaying a triple, double or mono-peaked behavior, depending on the system parameters. An analytical expression for the mean first passage time (MFPT) of the translocation process is derived, and provides an extensive characterization of the translocation process.
Electrospinning of Carbon Nanotube Reinforced Nanocomposite Fibrils and Yarns
Authors: Lam Hoa , Titchenal Nick , Naguib Nevin , Ye Haihui , Gogotsi Yury , Ko Frank 
Published: April 2011

ABSTRACTSingle wall (SWNT) and multi-wall carbon nanotubes (MWNT) were electrostatically assembled into nanofibers through an electrospinning process in order to increase the strength and toughness of polyacrylonitrile (PAN)-derived carbon fibers. It was found that the effectiveness of carbon nanotubes (CNT) in reinforcing the PAN precursor is highly dependent on the dispersion and the alignment of the CNT. Alignment was achieved during electrospinning by the flow of polymer, electrostatic charge and diameter confinement. Up to 10 wt. % SWNT co-electrospun with PAN was successfully produced with fiber diameters in the range of 40 nm to 400 nm. With the addition of 1 wt. % SWNT, a two-fold increase in strength and modulus was obtained in the as-spun nanofibers mat. These encouraging results show a promising pathway to produce the next generation of high performance carbon fibers that will help bridge dimensional and properties gap between nanoscopic and macroscopic structures.
Deposition of TiN/NbN Superlattice Hard Coatings by Ionised Magnetron Sputter Deposition
Authors: Long Yi , Stearn Robert J. , Barber Zoe H. , Lloyd Stephen J. , Clegg William J. 
Published: April 2011

ABSTRACTWe have investigated the effect of ion bombardment on the structure and hardness of thin coatings of TiN/NbN multilayered structures and monolithic films of both TiN and NbN. A radio frequency coil was used to generate an additional inductively coupled plasma between the substrate and the target enabling the sample to be bombarded by a high flux of relatively low energy ions under the appropriate conditions. It is shown that the effect of such bombardment in the case of the monolithic films is to reduce the porosity. This gave an increase in the hardness of both the TiN and the NbN films up to a power of 100 W (using a coil with a cross-sectional area of 2 × 103 mm2). Further increasing the power density led to a decrease in hardness. TiN/NbN multilayer coatings were made under the optimum deposition conditions for the monolithic materials and gave hardnesses greater than those observed in either TiN or NbN and approximately 50% greater than that predicted by a mixtures rule.
Size-Induced Tetragonal to Monoclinic Phase Transition in Zirconia Nanocrystals.
Authors: Baldinozzi Gianguido , Simeone David , Gosset Dominique , Dutheil Michael , Kusinski Jan 
Published: April 2011

ABSTRACTAccurate neutron powder diffraction experiments at D20, ILL Grenoble, allowed to monitor the reconstructive tetragonal to monoclinic phase transition as a function of the size of zirconia nanoparticles. In the nanocrystals, both phases are identical to the ones generally observed in micrometric zirconia. Rietveld refinements on these samples point out an increase of the tetragonal fraction and a decrease of the lattice parameters when the size of the particle decreases. An uniaxial strain depending on the grain size is also observed. The phase transition definitely occurs above a threshold crystal size. These results are analysed within the Landau theory and they can be understood as a mechanism of size-dependent phase transition where the primary order parameter is altered by the nanoparticle size.
Modeling and Characterization of Elastic Constants of Functionalized Nanotube Materials
Authors: Frankland S. J. V. , Herzog M. N. , Odegard G. M. , Gates T. S. , Fay C. C. 
Published: April 2011

ABSTRACTMolecular dynamics simulation and equivalent continuum modeling were used to calculate the elastic constants of 1,3-bis(4-aminophenoxy-4′-benzoyl) benzene (1,3-BABB)/single-walled carbon nanotube (SWNT) materials. The calculated Young's moduli are compared with storage moduli measured experimentally with nanoindentation. Excellent agreement is observed between the calculated and measured modulus values for the 1,3-BABB/SWNT materials.
Ultrathin Cu Films on Mo(110) Characterized by Helium Implantation
Authors: Venugopal Vinay , Thijsse Barend J. 
Published: April 2011

ABSTRACTPoint defects and thermal stability of ultrathin Cu films (3–200 Å) deposited on Mo(110) substrate at 300 K have been characterized using thermal helium desorption spectrometry (THDS). Implantation of the samples (10–100 Å Cu/Mo) with 1000 eV He+ aided in detecting He release from monovacancy in Cu films and desorption of the films (above 1200 K) from Mo substrate. A thickness dependent peak is identified in the helium desorption spectra, which is shown to be due to the process of island formation in the Cu films, using pre-implantation annealing treatments for the 40 Å film. Native defects in the films (3–200 Å) were probed using 75 eV He+ implantation.
Study on End-of-Range Defects Induced by Sb Implantation
Authors: Lai Yi-Sheng , Chen J. S. , Ho Y. S. , Sun H. L. , Huang K. B. 
Published: April 2011

ABSTRACTExtended defects formed by antimony ion implantation in Si(100) was investigated as a function of the implant energy. The implanted layer was examined by cross-sectional electron microscopy (TEM). Post-implantation spike-annealing was also performed from 950°C to 1095°C to examine evolution of defects. From the TEM study, the threshold energy to induce visible defects for Sb implantation was found to be more than 50 keV. A mapping for the location of defects was constructed by TEM and secondary ion mass spectroscopy (SIMS). The end-of-range (EOR) defects, which were possibly formed during the solid phase epitaixy regrowth, were located near the lower bound of the transition region. For 70-keV implantation, extended defects appear at the near-surface and the EOR region. It was observed that the near-surface defects diminished after annealing at more than 1050°C, while the EOR defects became coarsening at 1095°C.
Magnetic Properties in Fe-Ni Invar Alloys Irradiated by High-Energy Ions
Authors: Ono Fumihisa , Komatsu Seiji , Chimi Yasuhiro , Ishikawa Norito , Kambara Tadashi , Iwase Akihiro 
Published: April 2011

ABSTRACTAnomalously large shift of the Curie temperature has recently been observed in Fe-Ni Invar alloys irradiated with high-energy heavy ions. This large effect can be attributed to the large positive magneto-volume effect essentially originated in the itinerant electron ferromagnetism in Fe-Ni Invar alloys. To investigate the mechanism of the large modification of the ferromagnetism and the structure of the modified portion, measurements of the beam energy dependence of AC-susceptibility-temperature curves have been made. It was found that the amount of the shift of the Curie temperature did not change by increasing the beam energy. On the contrary, the intensity of the susceptibility of the modified portion increased with increasing the ion beam energy. The high-density electronic excitation is considered to be responsible for the large modification of the ferromagnetism in Fe-Ni Invar alloys.
Preparation and Patterning of GaSb Surfaces with Br-IBAE for Antimonide Based Molecular Beam Epitaxy
Authors: Vangala S.R. , Krejca B. , Krishnaswami K. , Dauplaise H. , Qian X. , Zhu B. , Ospina M. , Sung C. , Vaccaro K. , Bliss D. , Goodhue W.D. 
Published: April 2011

ABSTRACTBromine Ion Beam Assisted Etching (Br-IBAE) is shown to be useful in removing GaSb wafer chemical mechanical polish (CMP) surface and subsurface damage; creating microstructure patterns in GaSb surfaces through stencil, photoresist, and oxides masks; and stabilizing the as-etched GaSb surface with a thin, easily thermally desorbed oxide layer. Thus, the Br-IBAE technique is well suited as a GaSb surface final-polish technique in overgrowth applications that require “epi-ready” GaSb (100) surfaces for molecular beam epitaxy (MBE) as well as applications such as quantum wires and dots that require high-quality GaSb/AlInGaSb MBE overgrowth over patterned GaSb (100) surfaces.