bluuebunny/crossref_metadata_2025_split huggingface dataset:
RAMAN μ-SPECTROMETRY, A UNIQUE TOOL FOR ON-SITE ANALYSIS AND IDENTIFICATION OF ANCIENT CERAMICS AND GLASSES
Authors: Colomban Ph. 
Published: April 2011

ABSTRACTRaman micro-spectroscopy allows remote, non-destructive analysis of materials. Our laboratory was among the first to apply this technique to frescoes, oil and parchment painting. For five years we have focused our efforts on horn, ivory, tortoise shell and ancient ceramics and glasses. Crystalline and amorphous phases can be identified in both body and surface layer, including the glaze/glass-coloring nanosized pigments (e.g. in lustre ware, the first nano-optic device). Recent generation instruments are portable, which allows for on-site examination, for example, in a museum. In nanostructured, nanocrystalline/amorphous silicate glasses, glazes and most of their pigments, Raman parameters and their multivariable analysis are used to recognize compositions as well as to classify them as a function of their processing. This overview addresses the procedure, choice of the exciting radiation, control of the Raman resonance, data processing and extraction of relevant parameters such as the index of polymerization and different signatures that may be characteristic of specific glazes and pigments. Didactic examples are chosen among pottery that representative of the different production technologies used in the Roman, European (Medici, Meissen, Chantilly, Mennecy, Saint-Cloud, Sèvres), Islamic (Iznik, Kütahya, Safavid) and Asian (Vietnam) worlds.
Nanoparticles in Lustre Reconstructions
Authors: Fredrickx P. , Verbeeck J. , Schryvers D. , Hélary D. , Darque-Ceretti E. 
Published: April 2011

ABSTRACTIt is increasingly apparent that the spatial distribution of Ag and Cu nanoparticles in lustre glazes is an important factor in determining the colour displayed by the decoration. Using STEM-EDX of cross sections, this distribution can easily be imaged, as is demonstrated in two modern reconstructions of lustre decorations from Granada, Spain. On the nanoscale, the difference in colour can be related to a different spatial distribution of the Ag and Cu particles, with the brownish gold variant consisting of a top layer of Ag nanoparticles with an underlying layer of Cu nanoparticles while in the yellowish golden lustre Cu specks are unevenly dispersed.
Understanding Glass Deterioration in Museum Collections through Raman Spectroscopy and SIMS analysis
Authors: Robinet Laurianne , Eremin Katherine , Fearn Sarah , Pulham Colin , Hall Christopher 
Published: April 2011

ABSTRACTThe combination of Raman spectroscopy and Secondary Ion Mass Spectrometry can improve understanding of the chemistry of the glass alteration process. Formic and acetic acids play an important role in the alteration of museum glass objects placed in a humid atmosphere. Raman spectroscopy indicates that the soda-rich glass structure is modified differently when exposed to a humid versus a humid and polluted atmosphere at 60°C. Formic acid was not formed from soda-rich glass in the presence of carbon dioxide, high humidity and light.
Manipulation of Nickel Nanoparticles Deposited on HOPG
Authors: Atashbar Massood Z. , Bliznyuk Valery N. , Singamaneni Srikanth 
Published: April 2011

ABSTRACTNickel nanowires were fabricated by electrodepositing Ni from an aqueous plating solution onto the step edges of Highly Oriented Pyrolytic Graphite (HOPG). Freshly cleaved HOPG was exposed to a plating solution of nickel and electro chemically deposited by cyclic voltametry. The morphology of the deposited nanoparticles was studied using an Atomic Force Microscope (AFM) in non-contact mode. The magnetic force of interaction between the nanoparticles was studied by magnetizing the particles. The critical force to displace the nanoparticles was estimated using contact mode of AFM.
Nanomagnetic Structures: Fabrication and Interactions
Authors: Sellmyer David J. , Sui Y. C. , Xu Y. F. , Yan M. L. , Sorge K. D. , Skomski R. 
Published: April 2011

ABSTRACTMagnetic nanostructures with desirable properties such as monodispersed size and crystallographic texturing can be fabricated by a number of synthetic techniques. In this paper, we discuss methods for creating nanoclusters with fine control of individual propertiesand their interactions, as well as a promising chemical technique that provides control of several properties simultaneously. Current and potential applications also will be addressed.
Room-temperature magnetoresistance of one-dimensional magnetite (Fe3O4) nanostructures
Authors: Liu Zuqin , Zhang Daihua , Zhou Chongwu 
Published: April 2011

ABSTRACTIn this paper, we present our recent studies on the synthesis and magnetoresistance of single crystalline Fe3O4 core-shell nanowires and nanotubes. Homogeneous Fe3O4 nanowires/tubes with controllable length, diameter and wall thickness were synthesized. The as-prepared material composition and stoichoimetry have been carefully examined and confirmed with a variety of characterization techniques including XRD, EDS, XPS, and TEM. Magnetoresistance under different temperatures was systemically studied. Up to 1.2% room temperature magnetoresistance was observed in the as synthesized nanowires/tubes under a magnetic field of B = 1.8 T.
Stretchability of complex patterns of thin metal conductors on elastomeric skin
Authors: Lacour Stéphanie P. , Wagner Sigurd 
Published: April 2011

ABSTRACTWe have previously shown that 25nm thick gold stripes on 1mm thick silicone membrane retain electrical conduction when stretched up to 100% along their long dimension. To function as electrical interconnects in conformable integrated circuits, the metallization must be stretchable in arbitrary directions. Therefore we have made and tested the mechanical and electrical properties of complex conductor patterns including X and Y oriented lines and cross junctions. We find that the metal patterns continue to conduct under uniaxial stretching in the X or Y direction and under radial, biaxial stretching.
Kinetic Control of Dome Cluster Composition by Varying Ge Deposition Rate
Authors: McDaniel E. P. , Drucker Jeff , Jiang Qian , Crozier P. A. , Smith David J. 
Published: April 2011

ABSTRACTThe mean size of dome clusters grown by molecular beam epitaxy of pure Ge onto Si(100) at substrate temperatures, T, of 550°C and 650°C is deposition rate dependent. For samples with nominal Ge coverages near 8 ML (1 ML = 6.78 ×1014 atoms/cm2) and deposition rates between 1.4 and 17.5 ML/min, higher deposition rates decreased the mean dome diameter and increased the dome areal density. Additionally, the critical volume for the pyramid-to-dome transition decreases with increasing deposition rate for islands grown between T = 550°C and 650°C. By this measure, the Ge content of the dome clusters rises with increasing deposition rate. Quantitative, nm-resolved electron energy loss spectroscopy (EELS) measurements taken in a scanning transmission electron microscope confirm these results. For domes grown at T = 650°C with rates of 1.4 ML/min and 17.5 ML/min, EELS indicates 59% and 70% Ge compositions, respectively. These results show that dome cluster composition may be kinetically controlled by varying the Ge deposition rate.
Morphological Changes while Growing Nickel Monosilicide Nanowires
Authors: Kim Joondong , Anderson Wayne A. , Guliants Elena A. , Bunker Christopher E. 
Published: April 2011

ABSTRACTNickel monosilicide (NiSi) nanowires (NWs) have been fabricated in a DC magnetron system by the Metal Induced Growth (MIG) method. The NW growing stages were sequentially observed by scanning electron microscopy. Deposited Ni on SiO2 coated Si wafers has been first grooved and agglomerated by thermal heating at 575 °C. In the sputtering procedure, Ni as a catalyst reacted with sputtered Si forming clusters. Nanowires were grown in the same directions on each cluster. Raman spectroscopy and Energy Dispersive Spectroscopy indicated the NW composition as NiSi. The linear propagating property of NWs was used to form self-assembled nanobridges (NBs) in trenched Si wafers. The affinity of NWs can be used on various substrate materials with less thermal damage. NiSi composed MIG-NBs are promising candidates as nanoscale contacts due to the features of low resistivity and low temperature processing giving less potential damage on fabricated structures.
Molecular Dynamics Study of Grain Growth in Nanocrystalline Materials in the Presence of Dopants
Authors: Millett Paul C. , Panneer Selvam R. , Saxena Ashok 
Published: April 2011

ABSTRACTMolecular dynamics simulations of bulk nanocrystalline Cu with dopant atoms segregated in the grain boundary regions were performed to investigate the impediment of grain growth during annealing at constant temperature of 800K. In this parametric study, the concentration and atomic radii mismatch between the dopants and the host atoms were systematically varied to determine how to most effectively retard grain growth. It is found that samples with positive excess enthalpy (ΔH) underwent various degrees of grain growth; however, when ?H was negative, no coarsening occurred. Also, ΔH varied linearly with dopant concentration with the slope equal to the enthalpy of segregation, in agreement with previous theoretical work.
Trapping of Hydrogen in Carbon Nitride Films During or After High Temperature Heat Treatment
Authors: Ingram David C. , Kayani Asghar , Lanter William C. , DeJoseph Charles A. 
Published: April 2011

ABSTRACTThin films of carbon nitride deposited by ion beam assisted deposition or by magnetron sputter deposition typically contain a significant fraction of hydrogen, 1–30 atomic percent (at.%). In order to improve the thermal stability of the properties of the films, attempts have been made to minimize the hydrogen trapped during deposition. Such films typically have less than 5 at.% hydrogen. On heating these films in ultra high purity (99.999%) argon, it has been found that above 600°C they start to absorb significant amounts of hydrogen, this despite retaining their mechanical integrity. The composition of the films is determined using Rutherford Backscattering Spectroscopy in combination with Elastic Recoil Spectroscopy for detecting the hydrogen isotopes. In this paper, the possible sources of the hydrogen have been investigated by exposing the samples to deuterated water or deuterium gas during or immediately after the heat treatment.
Influence of Macro- and Nanotopography, Thin Film Thermomechanical Behavior and Process Parameters on the Stability of Thermocompression Bonding.
Authors: Stamoulis Konstantinos , Mark Spearing S. 
Published: April 2011

ABSTRACTThe quality of wafer-level, gold thermocompression bonds is critically dependent on the interaction between the wafer topography, the thin film properties, the process parameters and tooling used to achieve the bonds. This study presents mechanics modeling of the effect of wafer topography. An analytical expression for the strain energy release rate associated with the elastic deformation required to overcome wafer bow is developed. Furthermore, a simple contact yielding criterion is used to examine the pressure and temperature conditions required to flatten nano-scale asperities in order to achieve bonding over the full apparent area. The analytical results combined with experimental data for the interface bond toughness obtained from four-point bend testing indicate that the overall wafer shape is a negligible contributor to bond quality. A micro-scale bond characterization based on microscopic observations and AFM measurements show that the bond yield is increased with increasing bond pressure.
Thermal Processing of Polycrystalline NiTi Shape Memory Alloys
Authors: Frick Carl P. , Ortega Alicia M. , Tyber Jeff , Gall Ken , Maier Hans J. , El.M. A. , Liu Yinong 
Published: April 2011

ABSTRACTThe objective of this study is to examine the effect of heat treatment on polycrystalline Ti-50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress induced martensite, which is critical for optimizing mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. Subsequent heat treatments were carried out at various temperatures for 1.5 hours. Transmission Electron Microscopy (TEM) observations revealed that Ti3Ni4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti3Ni4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi.
on the relationship between the electric double layer and actuation in ionomeric polymer transducers
Authors: Akle Barbar J. , Leo Donald J. 
Published: April 2011

ABSTRACTIonic polymer transducers are soft actuators that perform large bending deflections when voltages on the order of 1–5 V are applied across their thickness. Previous work showed that actuation performance of ionic polymer transducers is strongly correlated with the capacitance due to surface charge accumulation. Increasing the capacitance of the actuator increases the motion of the charges and increases the strain produced under the application of an electric field. Ionomeric transducers consist of an ionomer, such as Nafion (a product of DuPont), sandwiched between two high surface area electrodes. An electric double layer is formed on the interface between the cathode and the adsorbed positive ions. A novel plating technique which was previously developed is used to vary the morphology of the polymer-electrode interface to investigate the parameters of importance to the formation of the electric double layer. Electromechanical transducer tests are performed as a function of electrode morphology to correlate surface charge accumulation with the deflection generated by the transducer.
Thermodynamic Driving Forces for Martensitic Phase Transformations in Shape-Memory Alloys
Authors: Jannetti C. , Bassani J.L. , Turteltaub S. 
Published: April 2011

ABSTRACTA macroscopic constitutive model for the martensitic phase transformations in single-crystal shape-memory alloys (SMAs) is developed in the framework of irreversible thermodynamics with internal variables. Central to the model is the notion that the rate of progression of structural rearrangements on the microscale depends on the stress state through the thermodynamic forces conjugate to the rearrangements. These thermodynamic forces, i.e. the driving forces for the phase transitions, are shown to have an important contribution that arises from changes in the effective elastic response of the SMA, which in turn depend upon the state of transformation. This contribution is shown to have a significant effect on the overall macroscopic stress-strain response.
Fluorination of Cup-stacked Carbon Nanotubes, Structures and Properties
Authors: Touhara Hidekazu , Yonemoto Akiko , Yamamoto Kazunao , Komiyama Shingo , Kawasaki Shinji , Okino Fujio , Yanagisawa Takashi , Endo Morinobu 
Published: April 2011

ABSTRACTCup-stacked carbon nanotubes (Cup-CNTs) was fluorinated in a temperature range RT-500• •by 0.5–1 atm elemental fluorine. The F/C atomic ratio (CF0.4-CF1.2) and the color are strongly dependent on the fluorination conditions. The color of fluorinated Cup-CNTs (F-Cup-CNTs) varies from black, through gray and yellow to white. The form and morphology of the pristine tubes were well preserved after fluorination, and the fluorination results in the functionalization and modification of pristine Cup-CNTs with respect to electrochemical properties. The F-Cup-CNTs as cathodes for primary Li cells discharge satisfactorily with 100% cathode utility.
Carbon Nanotube-Induced Planarization of Conjugated Polymers in Solution
Authors: Chen Jian , Ramasubramaniam Rajagopal , Liu Haiying 
Published: April 2011

ABSTRACTThe understanding of the conformational interaction between conjugated polymers and carbon nanotubes in solution is essential to develop the applications of carbon nanotubes, particularly conjugated polymer-carbon nanotube hybrid materials. The visible absorption spectroscopic study shows that curved carbon nanotube surfaces can induce the planarization of individual conjugated polymers such as poly(p-phenyleneethynylene)s and poly(3-alkylthiophene)s in solution. The impact of nanotube surface quality on the interaction between carbon nanotubes and conjugated polymers is investigated.
Polymer Functionalized Carbon nanotubes for sensor application
Authors: Vedala Narasimha Harindra , Choi Young C. , Zhou X. Y. , Kim Gene , Choi WonBong 
Published: April 2011

ABSTRACTSurface modification of carbon nanotubes with polyvinyl alcohol (PVOH) showed detection for humidity variation implying a possible application as a nanoscale humidity sensor. Wettability studies on single-wall, Y junction single wall and multiwall carbon nanotubes revealed that these nanotubes tend to become highly hydrophilic surfaces by this functionalisation. From the raman analysis it was determined that the majority of the nanotubes in our Y-junction single wall nanotubes were semiconducting in nature. The conductivity studies revealed that the Y junction nanotubes with PVOH functionalisation show large change in conductivity for varying relative humidity (RH). We propose a possible charge transport mechanism in these functionalized nanotubes.
An Experimental Estimate of the Free Energy of Formation of Single Walled Carbon Nanotubes
Authors: Wagg L. M. , Hornyak G. L. , Grigorian L. , Dillon A. C. , Jones K. M. , Blackburn J. , Parilla P. A. , Heben M. J. 
Published: April 2011

ABSTRACTSingle walled carbon nanotubes (SWNT) were synthesized by methane CVD on a supported mixed transition metal (Fe/Mo) catalyst. Gas feed composition and reaction temperature were varied to identify the threshold conditions for the growth of SWNT. These reaction conditions closely approximate pseudo-equilibrium conditions with some active reaction intermediate (likely chemisorbed carbon atoms) that proceeds to nucleate and grow SWNT. This value also serves as an estimated upper limit of the free energy of formation ΔG*(T)SWNT since the active intermediate proceeds to form SWNT through a process that is thought to be essentially irreversible. The difference relative to graphite is in good agreement with literature values predicted from simulations for SWNT nuclei containing approximately 80 atoms, while considerably larger than that predicted for bulk 5, 5 SWNT. Our estimate over the range 700 to 1000 °C of 16.1 to 13.9 kJ/mol is considerably greater than the free energy of formation for diamond (between 5.8 and 6.9 kJ/mol from 700 to 925 °C).
A Dual-RF-Plasma Approach for Controlling the Graphitic Order and Diameters of Vertically-Aligned Multiwall Carbon Nanotubes
Authors: Menda Jitendra , Vanga Lakshman Kumar , Ulmen Benjamin , Yap Yoke Khin , Pan Zhengwei , Ivanov Ilia N. , Puretzky Alex A. , Geohegan David B. 
Published: April 2011

ABSTRACTPlasma enhanced chemical vapor deposition (PECVD) is a unique technique for growing vertically-aligned multiwall carbon nanotubes (VA-MWNTs) at controllable tube densities. This technique is of considerable importance for low temperature growth of VA-MWNTs at desired locations. However, the graphitic order of these MWNTs is inferior to those grown by laser ablation, arc discharge, and thermal CVD techniques. Previously, these VA-MWNTs were grown by a one-plasma approach (DC, microwave etc), either for gas decomposition or substrate biasing. Here, we describe a dual-RF plasma enhanced CVD (dual-RF-PECVD) technique that offers unique capability for controlling the graphitic order and diameters of VA-MWNTs.
Homogeneous Dispersion of the Surface Modified MWNTs in the PU Matrix and Electrical Conductivity of the MWNTs/PU Composites
Authors: Kim Yoon Jin , Jang Yong Gyun , Choi Jun Whan , Yoon Ho Gyu 
Published: April 2011

AbstractDispersion characteristics of the surface modified MWNTs (Miltiwalled nanotubes) in the PU (polyurethane) matrix and electrical conductivity of the MWNTs/PU composites are investigated using SEM and DEA (Dielectric analyzer) with respect to the chemical treatment of MWNTs, the kind of surfactants and their content. Several chemical treatments of the MWNTs' surfaces were performed with the acids type, acidic concentration, treatment temperature, and oxidation time. All the surface of modified MWNTs are negatively charged and functionalized with carboxylic group; however, the external walls of some MWNTs were severely damaged so that they were frequently thinned and partially cracked. Compared to those of the composites without the addition of surfactant, the surfactant embedded into composites show much better dispersion of the MWNTs and higher electrical conductivity, these results are in good agreement with the two step adsorption model of cationic surfactants proposed by Y. Gao. Both the optimized MWNTs and cationic surfactant filled PU composites show very low percolation threshold, pc = 0.0089±0.007 vol. %, and relatively higher conductivity after percolation than other carbon nanotubes composite systems reported elsewhere.
Carbon nanotube growth on metal-catalyzed substrates in a laser oven apparatus
Authors: Suda Y. , Tanaka A. , Okita A. , Bratescu M. A. , Sakai Y. , Nakamura J. , Xiong G. Y. , Ren Z. F. 
Published: April 2011

ABSTRACTCarbon nanotubes (CNTs) were grown on Ni- and Fe-coated SiO2/Si substrates in a laser oven apparatus. The grown CNTs were analyzed by scanning electron microscopy. It is speculated that the CNTs grow out from the metal nanoparticle after laser-ablated carbon clusters have been dissolved in it. In a range of oven temperatures between 800 and 1100°C, growth of CNTs was achieved at a temperature ≥ 1000°C. The thickness of the Ni film controlled the CNTs diameter.