bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mechanism of Ductile Fracture in Constrained Thin Films
Authors: Kassner M.E. , Kennedy T.C , Schrems K.K. 
Published: April 2011

AbstractThe mechanism of low macroscopic-plastic-strain, ductile fractures under various high triaxial stresses in constrained thin silver films was investigated. Particular emphasis was placed on investigating ductile fracture by unstable cavity growth. The various multi-axial loads to failure were experimentally measured. FEA analysis was used to determine the corresponding high triaxial stress-states within the interlayer, also considering cavity-cavity interaction, residual stresses and elastic incompatibility stresses across interfaces. These were compared to the stresses required for cavity instability. Ductile fracture under high triaxial stresses, associated with low macroscopic strains, appears to be explained by unstable cavity growth, where cavity growth may occur without large macroscopic (e.g., < 0.05) plastic strains.
Atomic-Scale Structure and Properties of Thin Epitaxial SrRuO3 Films Grown on SrTiO3 (100) by Pulsed Laser Deposition
Authors: Satyalakshmi K.M. , Zakharov N. D. , Hesse D. , Koren G. 
Published: April 2011

AbstractTransition metal oxides with perovskite structure exhibit a wide range of electrical properties. SrRuO3 (SRO), a perovskite oxide with high conductivity, finds applications as an electrode layer in ferroelectric devices and as a barrier layer in superconductor-normal metal-superconductor (SNS) Josephson junctions involving high Tc superconductors. Here we report on the structure and properties of thin SRO films on SrTiO3 (100) substrates grown by pulsed laser deposition. AFM investigations revealed that the SRO films exhibit island growth. The island size increases with thickness, and at a typical thickness of about 20 nm a connected network of islands is formed. The resistivity of the SRO films grown at different substrate temperatures (700 °C - 850 °C) exhibits metallic behavior with a ferromagnetic transition at 150 K. The films with typical thicknesses of 20 nm, grown at a substrate temperature of 775 °C exhibited the lowest resistivity of 200 μΩ-cm at 300 K, whereas the films grown at lower (700 °C) and higher (850 °C) temperatures showed a much higher resistivity at 300 K. By AFM and high resolution TEM investigations, this behavior is correlated with the atomicscale structure of the films. The film with the lowest room temperature resistivity showed an almost defect-free orthorhombic structure, whereas the film grown at 850 °C contained structural defects in high density, such as SrO-rich antiphase boundaries and twins located at the boundaries between the islands. The films grown at 700 °C showed a cubic perovskite structure, which is obviously the reason for their high resistivity.
Influence of Ti additions on the Texture and Dielectric Properties of LSBN-BST Complex Ceramics
Authors: Portelles J. , Amorín H. , Siqueiros J. M. , Castilión F.F. , Martínez E. , Aguilera S. 
Published: April 2011

AbstractThe stoichiometric La-Ti doped strontium-barium niobate ceramic system was obtained for different concentrations of Titanium ions (Ti=1,3,5,10,30,50 %), where the Nb5− was substituted by Ti4+ according to the following expression Sr0.255 La0.03Bao0.7Nb2−yTiyO6−y/2 (LSBN-BST). The oxygen vacancies thus created which, together with the vacancies in the A sites of the tetragonal tungsten-bronze (TTB) material structure, have an important influence on their texture and dielectric properties, due to the crucial role of the occupancy of the crystallographic sites. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and thermoelectric analyses are reported. We report the first results for thin films of LSBNT- 7 % obtained by the PLD technique. The diffraction pattern reveals the presence of the LSBNT structure without annealing.
Ferroelectric Properties of SBT (Sr/Bi/Ta = 0.8/2.3/2) Thin Films Using a Novel Chemical Solution Deposition
Authors: Kim Seung-Hyun , Kim D.J. , Streiffer S.K. , Maria J-P. , Kingon Angus I. 
Published: April 2011

AbstractA new chemical route using an alkanolamine chelating agent for synthesis of ferroelectric Sro0.8Bi2.3Ta2O9 (SBT) thin films is investigated. The addition of alkanolamine provided stability to the SBT solution by retarding the hydrolysis and condensation rates. This solution could be stored for 30 days without any appreciable change of the properties. The crystallinity and the microstructure of the SBT thin films improved with increasing annealing temperature, and strongly influenced the ferroelectric properties. This alkanolamine modified films annealed at 800 °C exhibited low voltage saturation, high remanent polarization and resistance to fatigue after 1010 switching cycles. These electrical properties are favorable for non-volatile memory applications.
Control of Grain Size of Pb(Zr,Ti)O3 Thin Films by MOCVD and the Effect of Size on the Electrical Properties
Authors: Fujisawa H. , Nakashima S. , Shimizu M. , Niu H. 
Published: April 2011

AbstractThe grain size of MOCVD-Pb(Zr,Ti)O3 (PZT) thin films was successfully controlled by changing the grain size of Ir bottom electrodes and by changing the growth rate of PZT films. In Ir/PZT/Ir/SiO2/Si capacitors, the grain size of PZT thin films increased from 120 to 240nm as the grain size of bottom Ir electrodes increased from 50 to 200nm. The dielectric constants of PZT thin films increased from 760 to 1440 as the grain size increased from 120 to 240nm. Remanent polarization increased and coercive field decreased as the grain size increased. This dependence of electrical properties on the grain size coincided with that of ceramics.
The Effect of Atmospheric Water Vapour on the Temperature Dependence of Capacitance in BaxSr1−xTiO3 Thin Films
Authors: O'Neill D. , Gregg J. M. 
Published: April 2011

AbstractThin film ceramic Au/BaxSr(1−x)TiO3/YBCO/MgO planar capacitors with x ranging from 1 to 0.4 were fabricated using pulsed laser deposition (PLD). Structural and chemical characterisation showed the ferroelectric layers to be of perovskite crystallography, with cation stoichiometry close to that of the target. Auger depth profiling showed the interface between ferroelectric and lower electrode to be reasonably chemically sharp.Capacitance versus temperature measurements performed in air showed a pronounced difference in behaviour between bulk and thin film devices. Bulk samples exhibited the expected capacitance anomaly at the Curie temperature. In contrast, thin film capacitors showed a prominent peak in capacitance at temperatures between 7 and 25°C on heating, irrespective of composition and did not show any evidence of expected Curie anomalies.Further characterisation under vacuum and with deliberate additions of water vapour to the vacuum chamber indicated that the peaks observed in thin film devices described above could be attributed to the presence of atmospheric water vapour. This demonstrates that water vapour in the air can have a significant effect on the dielectric response of thin film capacitors around room temperature.Studies on higher quality films showed a reduced response to water vapour.
The Role of Precursor Chemistry in the Ferroelectric Properties of Donor Doped Pb(Zr,Ti)O3 Thin Films
Authors: Fè Laura , Malič B. , Norga G. , Kosec M. , Wouters D. J. , Bartic T. A. , Maes H. E. 
Published: April 2011

AbstractModified sol-gel processes have been developed for the preparation of precursor solutions of undoped, La and Ta doped PZT (25/75). These processes use different solvents (methoxyethanol, butoxyethanol) and different lead sources (lead acetate, lead oxide). Due to variations in the structure and in the composition of the solutions, significantly different thermal decomposition behaviors were found. These inevitably affected texture and microstructure of the sol-gel derived thin films, demonstrating the important role of precursor chemistry in the improvement of film properties. In the case of tantalum doped Pt/PZT/Pt ferroelectric capacitors a rectangular hysteresis loop, featuring high Pr, was obtained for one specific precursor chemistry.
Domain Structure of Poled Ferroelectric (111) PZT (PbZr0.25Ti0.75O3) Films
Authors: Zybill C.E. , Boubekeur H. , Radojkovic P. , Schwartzkopff M. , Hartmann E. , Koch F. , Groos G. , Rezek B. , Bruchhaus R. , Wersing W. 
Published: April 2011

AbstractFilms of (111) oriented self-polarized, tetragonal ferroelectric PZT crystallites on (100)Si/SiO2(250 nm)/(111) Pt (50 nm) have been investigated by STM, AFM and SAXS. After metallization of the PZT surface with a Cr-Ni film (5.2 nm thickness) or a Ti film (5.0 nm thickness), single domains were visible on the metal surface by STM measurements as parallel stripes. The lamellar stripes had a width of 10.5 – 25.2 nm and a vertical corrugation of 0.9 – 3.0 nm at the intersection line of the domain walls with the crystallite surface.High resolution AFM with EBD supertips on unmetallized samples revealed areas of typically several µm in diameter showing crystallites with perfectly parallel aligned (90°) domains of 10 - 15 nm width with their boundaries along {110} planes. Single domain walls were visible as a trace on the surface by a negative corrugation effect of 1.0 – 1.5 nm. This corrugation is assumed to be a reflection of the strain distribution normal to the surface. Furthermore, coherency (oxygen) defects are accumulated at the interface between 90 ° twin domains.SAXS investigations allowed to estimate a mean value of domain thickness of 17.5 nm. Exertion of stress (5.1 104Nm−2) to the film resulted in an increase of domain width by ∼1%.
High Dielectric Constant Hf-Ti-Sn-O Off-Axis Cosputtered Films
Authors: Schneemeyer L. F. , Dover R. B. van , Fleming R. M. 
Published: April 2011

AbstractNew Hf-Sn-Ti-O thin-film dielectric materials were explored using a compositional-spread approach. Thin films of composition Hf0.2Sn0.05Ti0.75O2 prepared at 250°C have excellent dielectric properties: 40-50 nm thick films with a dielectric constant of 40-60 were obtained, depending on the processing conditions, yielding a specific capacitance of 9-17 fF/µm2. Breakdown fields were measured to be about 4 MV/cm, yielding a Figure of Merit εε0Ebr=19 µC/cm2. Leakage currents, measured at 1 MV/cm, were in the range 10−7- 10−6 A/cm2. Film properties are strongly dependent on substrate temperature during deposition. Like their recently reported zirconium analogs, these materials are of interest for use in Si-IC device technology, for example as storage capacitors in DRAM.
Piezoelectric Films and Coatings for Device Purposes
Authors: Sayer Michael , Lukacs Marc , Olding Tim , Pang Guofeng , Zou Lichun , Chen Yan 
Published: April 2011

AbstractPiezoelectric devices generally require film thicknesses in the range 2-200µm and have a response which is perturbed by the substrate. Sol gel and sol gel composite technology provide a manufacturable process for many purposes with a piezoelectric coupling coefficient for 40ptm thick PZT approaching kt= 0.34. Techniques such as laser machining or micromolding are required for patterning thick devices. Measurement and applications of piezoelectric coatings in medical imaging, high temperature ultrasonics and flexure devices are discussed.
Epitaxial KNbo3 and its Nonlinear Optical Properties
Authors: Nichols Barbara M. , Wessels Bruce W. , Belot John A. , Marks Tobin J. 
Published: April 2011

AbstractThe nonlinear optical properties of epitaxial KNbO3 were studied for films grown by metalorganic chemical vapor deposition on different substrates. X-ray diffraction revealed epitaxial KNbO3 with a (110) orientation for layers deposited on single crystal strontium titanate. Whereas, films grown on (100) spinel exhibited a multi-variant structure, consisting of the (110) and (001) orientations. The volume fraction of each crystallographic variant in the film was calculated. Second harmonic generation measurements at 532 nm were performed to determine the ferroelectric domain variants present. The Maker-fringe technique was employed to obtain the effective nonlinear optical susceptibility of the films, which ranged from 0.1 - 1.8 pm/V. The SHG intensity profiles reveal a strong dependence upon substrate type.
Control of Ferroelectric Properties of PbZrxTi1−xO3 Thin Film for Electron Emission Device Driven by Low Voltage
Authors: Yamagata Y. , Yamazato M. , Ikegami T. , Ebihara K. , Narayan J. , Grishin A.M. 
Published: April 2011

AbstractEpitaxial PbZr0.52TiO0.48O3/YBa2Cu3O7−x heterostructures on Nd:YAlO3 and MgO substrates were fabricated by KrF pulsed laser deposition. The coercive electric field of the PZT films increased with decrease of the film thickness from 1.2 μm to 0.04 μm, while the magnitude of spontaneous polarization was almost constant in this thickness range. It was found that the dependence of the film thickness d on the coercive electric field Ec was Ecæ d−2/3. This results from that the PZT/YBCO heterostructure has the one dimensional ferroelectric domain growth without non-ferroelectric phase. The polarization of AuIPZT/YBCO/(MgO or YAlO) capacitors can be changed by the applied voltage below 5 V.
Effect of Solvent Condition on the Dynamic Response of Polymer Brushes
Authors: Kilbey S. M. , Schorr P. , Tirrell M. 
Published: April 2011

AbstractThe frictional response of two opposing polymer brushes subjected to steady shear was studied as a function of solvent condition and degree of compression using the Surface Forces Apparatus (SFA). The brushes were made by preferential adsorption of polyvinylpryridinepolystyrene (PVP-PS) block copolymers adsorbed onto atomically smooth surfaces from a dilute solution of toluene. Extremely parallel lateral motion was imparted to one surface and the response was detected at the opposing brush-covered surface. When the brushes were bathed in a good solvent, it was necessary to strongly compress the layers in order to observe frictional forces transmitted between the surfaces. However, when the solvent was changed to a near-theta solvent, large frictional forces were measured at weaker compressions. The onset of these frictional forces occurred at distances comparable to the distance at which the opposing layers contact one another and rapidly increase as the brushes are compressed. Arguments are advanced that this behavior is attributable to frictional interactions between the polymer chains and the solvent.
Wetting Of Ion Containg Polymers: Micelles Versus Molecular Absorption
Authors: Hill T. A. , Jiao X. , Martin C. W. , Demarteau D. D. , Perahia D. 
Published: April 2011

AbstractThe wetting behavior of perfluorinated ionomers has been investigated as a function of polymer-surface interaction, the nature of the counter-ion and the structure of the polymer in the solvent from which it has been cast onto the surface. Two different ion-containing polymers, with a per-fluoro-carbon backbone were studied. They differ in the chemical composition and the polarity of their side chains. AFM results together with neutron reflectivity, light scattering and surface tension measurements had shown that the structure of the polymer in the parent solution has a profound effect on the wetting properties as well as the surface structure of the polymers.
Crossover Time Behavior in a+b⃗c And a+2b⃗c Reaction-Diffusion Front Systems in a Capillary
Authors: Park Sung Hyun , Yen Andrew , Shi Zhong-You , Kopelman Raoul 
Published: April 2011

AbstractThe crossover time from the early-time regime to the asymptotic regime for the A+B⃗+C reaction-diffusion system with initially separated reactants has been derived analytically by matching the rate expressions for the two regimes. The crossover time expression thus obtained shows an explicit dependence on the rate constant (k) and the initial reactant concentrations (ao, bo). For the A+2B⃗C system we performed computer simulations using two different methods. Crossover behaviors for the global reaction rate and reaction front width have been observed for both methods. The crossover time depends on the mechanism of the reaction.
Monte Carlo Study of Etching at Silica-Water Interface
Authors: Yen Andrew , Zhao Xiaolin , Kopelman Raoul 
Published: April 2011

AbstractA surface adsorption-diffusion-reaction model is proposed and tested by Monte Carlo simulations. The solvent shell effect is considered as a geometric constraint and the Langmuir adsorption mechanism is also incorporated. An anomalous power law of t1/2 is obtained for the amount of material removed from the surface vs. time. The result agrees well with etching experiments of SAM on a silica surface. We conclude that the unusual power law results from an interplay of vacancy growth and fusion at the surface.
Material Selection and Layered Assembly for Shock Wave Attenuation
Authors: Segars R. A. , Piscitelle L. 
Published: April 2011

AbstractTheoretical models and experimental data taken primarily from the literature provide predictive capabilities of the sound speed in porous materials and hence their acoustic impedance can be determined. Applying the acoustic approximation (weak discontinuity) at the interfaces of the porous material along with an attenuation model describing conditions within the porous system good fits to shock tube data on an elastomeric foam and on layers of kevlar were obtained.
Localized Optical Excitations and Two-Exciton Spectroscopy of Phenylacetylene Dendrimers
Authors: Chernyak V. , Poliakov E. Y. , Tretiak S. , Mukamel S. 
Published: April 2011

AbstractThe one- and two-exciton manifolds of conjugated dendrimers possessing fractal geometries are studied using the Frenkel exciton model. Two-photon spectra can be used to determine both the magnitude and the sign of short-range coupling among segments. Self-similarity and the high degree of symmetry make it possible to compute the one-exciton states and the optical response with reduced numerical effort that scales linearly rather than exponentially with the number of generations. The third-order optical response and exciton scattering matrix are expressed in compact forms using irreducible representation of optical excitations, totally avoiding the expensive explicit calculation of two-exciton eigenstates.
Selective Grafting of Amine Groups on Polyethylene by Means of Modulated RF NH3 Plasmas
Authors: Creatore M. , Cicala G. , Favia P. , Lamendola R. , d'Agostno R. 
Published: April 2011

AbstractPlasma treatments in power modulated NH3 RF glow discharges have been performed for modifying the surface of polyethylene (PE). Time Resolved Optical Emission Spectroscopy (TR-OES) has been utilized for monitoring the emission of active species during the modulation period of the discharge, Electron Spectroscopy for Chemical Analysis (ESCA) has been used for studying the surface composition of PE before and after the derivatization of plasmagrafted -NH2 groups. We present our preliminary results here, which show how modulated NH3 plasmas can effectively improve the grafting selectivity of -NH2 respect to all other N-containing groups.
Deposition of Transparent Conductive Tin Oxide thin Films by Pacvd for Sensor Applications
Authors: Arefi-Khonsari F. , Hellegouarc'h F. , Planade R. , Amouroux J. 
Published: April 2011

AbstractNon stoichiometric thin tin oxide films have been deposited using the PACVD technique in a RF glow discharge diode or triode reactor at low pressure (15 Pa) and at low temperature (25–100°C). The films deposited in the diode configuration were amorphous and presented a high transmittance (95%) in the visible region. The conductivity of the films deposited in the triode configuration can be increased by 4 orders of magnitude with respect to the ones deposited in the diode configuration (from 0.01 to 100 ω−1 cm−1) with a decrease of the gap energy (from 3.5 to 2.5 eV). This increase of the conductivity was accompanied by a slight decrease of the grain size (95 to 45 nm). The very small grain size of the deposited films makes them excellent candidates for gas sensors due to their good sensitivities to different molecules such as ethanol and propane.
Ultra High Rate, Wide Area, Plasma Polymerized Films from High Molecular Weight/Low Vapor Pressure Liquid or Liquid/Solid Suspension Monomer Precursors
Authors: Affinito J. D. , Gross M. E. , Mounier P. A. , Shi M-K , Graff G. L. 
Published: April 2011

AbstractA new process has been developed for the high rate vacuum deposition of solid films from high molecular weight/low vapor pressure liquid, or even liquid/solid suspension, monomer precursors. The gas resulting from the flash evaporation of a liquid monomer mixture, or from a suspension of insoluble solid particles in liquid monomer, is used as the support medium for a glow discharge in a Plasma Enhanced Chemical Vapor Deposition-like (PECVD) process. Due to the high molecular weight/low vapor pressure nature of the precursors, the plasma of the flash evaporated gas cryocondenses at extremely high rate on substrates at ambient, and higher, temperatures. Upon condensation the liquified plasma immediately begins to polymerize to form a solid film due to the high concentration of radicals and ions contained in the liquid film. The process has been successfully implemented in a vacuum roll coating system in a roll-to-roll deposition process. Polymer films, Molecularly Doped Polymer (MDP) composite films of polymer containing light emitting organic molecules, and MDP composite films of polymer containing organic dye molecules have been deposited at thicknesses ranging from 0.1 microns to 24 microns at webs speeds as high as 96 linear meters per minute. This new deposition process will be discussed along with some properties of the films fabricated with this new process.
Transition from Surface Treatment in a Batch Process to a Continuous Process
Authors: Holländer A , Royer E. , Behnisch J. 
Published: April 2011

AbstractFor the improvement of the adhesion to ethylene vinylacetate copolymer (EVA), poly (ethylene terephthalate) (PET) films were treated with low pressure plasmas in a laboratory batch reactor and in a pilot scale semi-continuous treatment system. The effects of the treatments were investigated by mechanical testing of the PET-EVA laminates, by XPS, by chemical derivatization for XPS, and by contact angle measurements including a data processing for the determination of Lewis acid/ base properties of the surfaces. It was found that the adhesion between the polymer surfaces seems to be based on rather specific interactions which ask for certain conditions for the surface treatment. The differences between the batch treatments and the semi-continuous treatments are discussed.
Thin Film Plasma Deposition of Allylamine; Effects of Solvent Treatment
Authors: van Os M. T. , Menges B. , Förch R. , Knoll W. , Timmons R. B. , Vancso G. J. 
Published: April 2011

AbstractAmine-functionalized thin films were prepared by plasma induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed plasma conditions to control the film chemistry, all other process variables being held constant. Using plasma polymerized films for subsequent grafting reactions or for direct biomedical applications usually involves exposure of the films to a solvent environment. It was the major focus of this work to investigate both the chemical and physical effects of solvents on plasma polymerized allylamine films. Film properties were determined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Waveguide Mode Spectroscopy (WaMS) and Surface Plasmon Spectroscopy (SPS). WaMS provided an ideal opportunity to study the complex swelling and drying behaviour of these films by allowing a simultaneous study of the changes in film thickness and refractive index. Although the amine groups of the monomer were increasingly retained in the films as the RF duty cycle was lowered, a larger amount of oxygen was also found to be incorporated upon exposure to air. Extraction in ethanol led to a decrease in film thickness, especially for the films produced at low duty cycles, but appeared to have little effect on the film composition, as measured by XPS and FTIR.