bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite Element Analysis of the Precracked Line Scratch Test
Authors: Volinsky A.A. , Mercado L. , Sarihan V. , Gerberich W.W. 
Published: April 2011

ABSTRACTIn MEMS packages and silicon devices, the adhesion of interconnects to the substrate is a critical reliability issue. A Precracked Line Scratch Test (PLST) is among one of the available tests to measure the thin line adhesion. In the test, an initial crack is introduced at the interface between the thin line and the substrate. The line is then loaded from the precracked end. The load is recorded continuously while the crack propagates before and after the line buckles. This precracked line scratch test has been applied earlier to tungsten thin lines on silicon wafers [1]. A macroscopic version of the test was also performed to evaluate the analytical model [2]. In the macroscopic tests, polycarbonate lines were bonded to steel substrates with cyanoacrylate.In this paper, finite element analysis is performed for the Precracked Line Scratch Test before line buckling. The energy release rates and phase angles are calculated based on the corresponding load and crack length. The results are then compared to the closed-form solution. Macroscopic experimental model along with the finite element solution has provided a way to derive the interface fracture toughness as a function of the crack length based on the load and crack length history. With the analysis in place, the precracked line scratch test can be used conveniently to study the adhesion of interconnects to passivation layers, MEMS devices and packages on different scales.
High Temperature, High-Pressure Fluid Connections for Power Micro-Systems
Authors: Harrison Todd S. , London Adam P. , Spearing S. Mark 
Published: April 2011

ABSTRACTHigh power density micro-systems offer the potential to revolutionize technologies for portable electrical power generation, propulsion and flow control. Devices are being designed and fabricated which include micro-gas turbine engines, micro-rocket engines, micro-motor- compressors, micro-pumps and micro-hydraulic transducers. Common to all of this family of devices is the need to create packages that service the devices, and interface them with the macro-scale environment. Fluid interconnections are a particularly demanding packaging element for this class of devices. In order to achieve high power densities, these devices are required to operate at high pressures and, in some cases, high temperatures. This paper describes the design, analysis, fabrication and testing of high-pressure, high temperature fluid connections for the micro-engine and micro-rocket applications. A glass bonding technology has been developed to allow the creation of multiple fluidic connections consisting of Ni/Fe alloy tubes to silicon devices. Key strategies to achieve high strength connections are: to minimize the mismatch in coefficients of thermal expansion between the components, to eliminate voids from the glass and to promote adequate wetting of the glass to both the tubes and the silicon. Mechanical test results are presented which correlate the strength and statistical reliability of such bonds to the processing conditions, choice of glass and surface preparation prior to bonding. Successful examples of packaged micro-engine and micro-rocket devices are presented.
The Characterization of TiNi Shape-Memory Actuated Microvalves
Authors: Lai B.-K. , Hahm G. , You L. , Shih C.-L. , Kahn H. , Phillips S. M. , Heuer A. H. 
Published: April 2011

ABSTRACTCo-sputtering has been used to fabricate equiatomic thin films of TiNi, a shape memory alloy, which form the basis of microactuators with many applications in MEMS. The stress evolution of TiNi films will be described. The performance of the TiNi actuators has been characterized, with regards to actuation force, recoverable strain, time response, and fatigue resistance. The performance of microvalves using these actuators will also be presented.
Microbridge Testing of Silicon Oxide/Silicon Nitride Bilayer Films
Authors: Qian C.-F. , Su Y.-J. , Zhao M.-H. , Zhang T.-Y. 
Published: April 2011

ABSTRACTThe present work further develops the microbridge testing method to characterize mechanical properties of bilayer thin films. A closed-form formula for deflection versus load under small deflection is derived with consideration of the substrate deformation and residual stress in each layer. The analysis shows that the solution for bending a bilayer beam is equivalent to that for bending a single-layer beam with an equivalent bending stiffness, an equivalent residual force and a residual moment. One can estimate the Young's modulus and residual stress in a layer if the corresponding values in the other layer are known. The analytic results are confirmed by finite element calculations. The microbridge tests are conducted on low-temperature-silicon oxide (LTO)/silicon nitride bilayer films as well as on silicon nitride single-layer films. All microbridge specimens are prepared by the microfabricating technique. The tests on the single-layer films provide the material properties of the silicon nitride films. Then, applying the proposed method for bilayer films under small deflection yields the Young's modulus of 37 GPa and the residual stress of -148 MPa for LTO films.
Dissipation and anisotropy in ultrathin YBa2Cu3O7/PrBa2Cu3O7 superlattices
Authors: Villegas J.E. , Gonzalez E.M. , Vicent J.L , Sefrioui Z. , Varela M. , Santamaría J. 
Published: April 2011

ABSTRACTUltrathin superlattices of 123 superconducting cuprates have been fabricated by high oxygen pressure sputtering technique. The superlattices show high quality, with negligible step disorder, roughness and interdiffusion. The insulating PrBa2Cu3O7 (PBCO) layer thickness has been kept constant at 5 unit cells (u.c.) and the superconducting YBa2Cu3O7 (YBCO) layer thickness has been changed from 8 u.c. to 1 u.c. In these uncoupled multilayers the critical temperature (Tc0) changes from 44 (1 u.c. YBCO) to 80 K (8 u.c. YBCO). In the vortex liquid regime, at constant temperature, the angular dependence of the magnetoresistance scales down with the applied magnetic field values in all the temperature range. This behavior allows us to study the anisotropy and dimensionality behavior of the mixed state in ultrathin superlattices. A dimensional crossover 3D-2D is found in the anisotropy with the 1 u.c. YBCO superlattices following a pure 2D behavior.
Micron-Thick Sr-Based (Hg,Pb)-1223 Films with jc(77K) of above 106 A/cm2
Authors: Klimonsky S.O. , Samoilenkov S.V. , Gorbenko O.Yu. , Kiryakov N.P. , Emelianov D.A. , Liashenko A.V. , Lee S.R. , Kaul A.R. , Andrianov D.G. 
Published: April 2011

ABSTRACTFor the first time the (001)-oriented Sr-based (Hg,Pb)-1223 films have been synthesized using the two-step procedure. Hg-free precursor films with the thickness of 1 μm have been deposited by MOCVD or PLD and then the films were annealed in sealed quartz ampoules together with synthesised (Hg,Pb)-1223 ceramics or a pressed precursor mixture of the same cation composition. No post-annealing in oxygen was used for these films. The phase composition of the PLD-films depended crucially on the deposition temperature of the precursor films. The best MOCVD films contained predominantly (Hg,Pb)-1223 and small amounts of non-superconducting phases according to XRD. The Tc=118 K and jc(77K,0.01T) = 2.5×106 A/cm2were measured for the MOCVD-samples.
Metal Organic Deposition of REBa2Cu3O7-y Films from Metal Trifluoroacetate Precursors
Authors: Honjo Tetsuji , Fuji Hiroshi , Huang Daxiang , Nakamura Yuichi , Izumi Teruo , Shiohara Yuh 
Published: April 2011

ABSTRACTMetal organic deposition (MOD) process using metal trifluoroacetate (TFA) precursors was applied to the Nd1+XBa2−XCu3Oy (Nd123) and the Tc dependence on experimental conditions such as the oxygen partial pressure (PO2) and the substrate temperature (Ts) for annealing was investigated. Thin films grown on SrTiO3 substrates at Ts = 800°C under PO2 = 300 ppm showed a Tc value of 89 K. However, from the results of TEM-EDS measurements, the substitution values of x in the Nd123 films increased from the substrate toward the surface in the film. These experimental results could be thermodynamically explained by the following model. The basic idea of the model is that the Ba potential in the precursor decreases by coarsening of BaF2 particles during the annealing for the Nd123 crystal growth. This model predicts that the small substitution value can be obtained with a higher growth rate of the Nd123 phase under low PO2.
Magnetic Field Dependence of Critical Current Density of TFA-MOD Processed YBCO Coated Conductors
Authors: Yamada Yutaka , Kim SeokBeom , Araki Takeshi , Yuasa Toyotaka , Takahashi Yasuo , Kurosaki Haruhiko , Shiohara Yuh , Hirabayashi Izumi , Iijima Yasuhiro , Takeda Kaoru 
Published: April 2011

ABSTRACTYBCO films on LaAlO3and IBAD (YSZ/Hastelloy) substrate were made by TFA-MOD (metalorganic deposition using trifluoroacetate) process. Improved coating solution resulted in high Jc at 77.3K and 0T of 7 MA/cm2 and 1.7 MA/cm2 for LaAlO3 and IBAD substrates, respectively. The magnetic field dependence of Jc at 77.3K also showed superior property: 105 A/cm2 at 4T (B//c-axis) for the LaAlO3substrate and at 3T (B//c-axis)) for IBAD substrate. Furthermore, the difference in Jc between single crystal LaAlO3and IBAD was small up to 3T. The present results imply that TFA-MOD process is promising for the practical YBCO coated conductor process.
Effect of YBCO film characteristics on RF properties of MSL resonators with these films
Authors: Yamanaka Kazunori , Akasegawa Akihiko , Nakanishi Teru 
Published: April 2011

ABSTRACTThe effect of YBCO film characteristics on the RF properties of microstrip-line (MSL) resonators using two surface resistance Rs value types of films was investigated in terms of weak links. The films were characterized in both cystallinity and microstructure. The RF properties of the resonators were measured at frequencies of about 2 GHz. It was understood that the film samples with higher Rs at 70 K, which exhibited strong c-axis orientation, both the 90 and 45- degree angle grains in plane of the films, Y211 segregation, and porous structures show large influence on RF magnetic field dependence of normalized resonant frequency-shift Δfc/fc, compared with the lower Rs type. On the other hand, the films with lower Rs at 70 K had much stronger c-axis orientation, the 90-degree angle grains, and dense structures. Consequently, it was considered that the lower Rs type films possessed fewer weak-links compared with the higher Rs type films, suggesting that the misorientation in the higher Rs films result in weak-links.
Magneto-optical study of grain boundaries, interfaces and grain boundary networks in YBaCuO
Authors: Jooss Ch. , Kautschor L.-O. , Delamare M.P. , Bringmann B. , Guth K. , Born V. , Sievers S. , Walter H. , Dzick J. , Holzmann J. , Freyhardt H. C. , de Boer B. , Holzapfel B. , Sandiumenge F. 
Published: April 2011

ABSTRACTUsing quantitative magneto-optics and an inversion scheme of Biot-Savart's law the local current carrying capability of various types of grain boundaries (GB's) and interfaces in YBaCuO thin films and bulk material was investigated. In all GB's and interfaces a spatial variation of the local critical current density jc was observed which, however, has different reasons, such as microstructural inhomogeneities, magnetic field dependence of jc and size effects in extended GB's and networks of low angle grain boundaries (LAGB's).
Jc Enhancement in Melt Textured YBCO with Different 211 Content by Fast Neutron Irradiation
Authors: Köhler Anke , Plain Jérôme , Seeböck Wolfgang , Puig Teresa , Carrillo Anna E. , Weber Harald W. , Obradors Xavier 
Published: April 2011

ABSTRACTMelt textured YBCO samples with and without 211 inclusions were irradiated by fast neutrons. The enhancement of the critical current density was studied as a function of the 211 content by means of SQUID magnetometry at temperatures from 5 to 77 K and magnetic fields from 0 to 8 T. The highest enhancement factor, found at 77 K and 1.5 T for a 211-free sample, is 27. The enhancement is less effective for samples with 211 inclusions. However, the critical current densities after irradiation show a similar temperature and field dependence in all samples. The role of the initial microstructure on the radiation effects is discussed.
Inter-chain Interaction of Metallic 1D-chain in PrBa2Cu4O8
Authors: Horii Shigeru , Takagi H. , Ikuta H. , Mizutani U. , Yamada Y. , Hirabayashi I. , Shimoyama J. , Kishio K. 
Published: April 2011

ABSTRACTThe a- and b-axis resistivities and the a-axis magnetoresistivities applying magnetic field (B) along all three crystallographic axes in non-superconductive PrBa2Cu4O8 single crystals have been measured using four-probe method. Resistivitiy along the b-axis (parallel to double-chains) showed a highly conductive behavior, of which the origin is attributed to the double-chains because of a large anisotropic conduction between a- and b-axis directions. However, a metallic behavior along the a-axis was also observed in temperature region below 130 K, which could be understood in terms of presence of finite and coherent inter-chain interaction along the a-axis direction. This conclusion is derived from good agreement with values of mean-free path length in the double chain, lchain estimated from both the ρb-T curve and the a-axis MR applying B//c using quasi-one-dimensional (quasi-1D) band model.
High-Temperature Superconducting Tapes Deposited by the Non-Vacuum, Low-Cost Combustion Chemical Vapor Deposition Technique
Authors: White Marvis K. , Campbell Ian H. , King Adam C. , Krebs Steve L. , Mattox Dave S. , Polley Todd A. , Shoup Shara S. , Xue Yibin 
Published: April 2011

ABSTRACTThe enormous technological potential of high-temperature superconductors (HTS) was realized immediately following their discovery in 1986, yet these materials largely remain laboratory curiosities as scientists struggle to scale from coupons to long lengths of practical coated conductor. Although both vacuum and non-vacuum processes are being investigated for commercial production, low-throughput vacuum techniques were the first to succeed in producing the buffer and superconducting layers necessary for superconducting tape with high critical currents. However, vacuum processes are not only expensive but impractical when addressing the needs for rapid production of kilometer lengths of wire. The innovative Combustion Chemical Vapor Deposition (CCVD) method used with the Rolling Assisted Biaxially Textured Substrates (RABiTS™) technology has shown significant promise in fabricating the multi-layer structures necessary for successful HTS tape while overcoming many of the shortcomings of traditional vacuum techniques. The key advantage of the CCVD technology is its ability to deposit high quality thin films in the open atmosphere using inexpensive precursor chemicals in solution. As a result, continuous, production-line manufacturing is possible with significantly reduced capital requirements and operating costs when compared to competing vacuum-based technologies. The current status of development for production of long lengths of high-temperature superconductors using CCVD will be discussed.
Some Organic-Inorganic Composites, Illustrative Simulations on Elastomer Reinforcement, and an Overview of Symposium Contributions
Authors: Mark J. E. 
Published: April 2011

ABSTRACTThis review first describes organic-inorganic composites which have been prepared using techniques similar to those employed in the new sol-gel approach to ceramics. Organometallics such as silicates, titanates, and aluminates are hydrolyzed in the presence of polymer chains (for example polysiloxanes and polyamides) that typically contain hydroxyl groups. The functional groups are used to bond the polymer chains onto the silica, titania, or alumina being formed in the hydrolysis, thus forming novel organic-inorganic composites. When the polymer chains are present in excess, they constitute the continuous phase, with the ceramic-type material appearing as reinforcing particles. When present in smaller amounts, the polymer is dispersed in the continuous ceramic phase, to give a polymer-modified ceramic. Under some conditions,bicontinuous systems are obtained.The second part addresses one of the major unsolved problems in the area of rubberlike elasticity, specifically a molecular understanding of the mechanisms by which the mechanical properties of elastomers are improved by the incorporation of particulate fillers such as carbon black or silica. Theoretical work on the reinforcement thus obtained is illustrated by some Monte Carlo calculations on one aspect of the problem, namely excluded volume effects of the filler particles on the network chain configurations. The resulting end-to-end distributions are then used in standard molecular models to generate stress-strain isotherms, which document the nature of the reinforcement obtained.The final part provides an overview of the specific papers presented at this symposium, and attempts to place them into the broad general context of “Filled and Nanocomposite Polymer Materials”.
Nanostructures from POSS-Grafted Block Copolymer Precursors
Authors: Chun Seung B. , Mather Patrick T. 
Published: April 2011

ABSTRACTA new method to prepare novel nanocomposites has been studied in which a polyhedral oligomeric silsesquioxane (POSS) monomer is grafted to a polyisoprene-block-polystyrene copolymer to yield an inorganic-organic hybrid copolymer (POSS-g-PI-block-PS). PS-block-PI copolymers (SI) were synthesized via anionic polymerization in tetrahydrofuran (THF) as solvent. The polyisoprene block of the SI diblock copolymers in this study featured a very high vinyl group fraction (65 mole % of 3,4- addition and 35 mole % of 1,2-addition) available to react with hydride-substituted POSS (isobutyldimethyl silane-POSS) to form a grafted block copolymer. Due to the immiscibility between POSS-grafted PI block and PS block, the grafted block copolymer developed a microdomain structure. The volume fraction of PS block in the grafted block copolymer was varied in the range of 0.45 to 0.37 in order to yield cylindrical PS microdomains in the matrix of POSS-grafted PI. After exposure to an oxygen plasma, it is expected that preferential erosion of the grafted block copolymer will occur for the organic potion (PS microdomains) thus leaving a well-defined nanoporous surface structure for nonlithographic functionalization of coated substrates.
“Green” nano-composite materials - new possibilities for bioplastics1
Authors: Fischer Sabine , de Vlieger Jan , Kock Theo , Batenburg Lawrence , Fischer Hartmut 
Published: April 2011

ABSTRACTResearch in the area of biological renewable materials has shown that the main building blocks of life – carbohydrates, fats, proteins, and their derivatives - could substitute products from traditional nonrenewable sources. However its realization will need significant and continuous improvement of those materials. Problems of applications of bioplastics arise not only from the (price) competition with the highly developed synthetic polymers but also from their, up to now not sufficient property levels. Possibilities to decrease the hydrophilicity and to increase the values of mechanical properties so far are: i) application of hydrophobic coating(s); ii) blending with different, biodegradable synthetic polymers (polyesters) and iii) new ways of reactive extrusion of natural. A new possibility in this direction is seen in the creation of composite materials of thermoplastic organic biopolymer and nanoscopic inorganic particles incorporated on a molecular scale.This paper will show the results of the first experiments to get nano-scale starch/clay composites. The starch will be fully gelatinized and the modified clay can be dispersed homogeneously on a truly nanoscale. Therefore all requirements of a significant increase in mechanics and a decrease in permeability of this composite material are present.
Influence of Filler Particles and Filler Clusters on Phase Separation in Binary Polymer Blends
Authors: Jiang Y. , Saxena A. , Lookman T. , Douglas J. F. 
Published: April 2011

ABSTRACTMotivated by recent experiments on filled polymer thin films, we study the effect of the presence of filler particles on phase separating mixtures. Using a generalized Cahn-Hillard-cook model, we show that the preferential wetting of one phase on the filler surface generates transient composition waves in the phase separating blends. The interference of the composition waves from different particles can stabilize the transient patterns, leading to desirable control of the morphology.
The Synthesis of Liquid Crystalline Polymer on Gold Nanoparticles
Authors: Fu Qinghong , Seery Thomas A. P. 
Published: April 2011

ABSTRACTGold nanoparticles with thiol stabilizing layers were prepared with various fractions of end-functional thiols. Alcohol end-groups were further elaborated to norbornyl moieties so that a ruthenium alkylidene initiator could be tethered to the nanoparticle surfaces. In two different nanoparticle formulations the functional thiols possessed hydrocarbon chains that held the metal centers either near to or far from the surface of the thiol stabilizing layer. The tethered organometallic complexes were used to initiate polymerization from the nanoparticle surfaces. Liquid crystalline polymer was grown from nanoparticles where the metal center was tethered far from the surface but polymerization could not be initiated when the metal centers were held close to the surface. We hypothesize that steric hindrance is controlled by the length of the tethering thiol. Polarized optical microscopy showed that the polymer coated gold nanoparticles could still form a nematic mesophase at elevated temperature although the orientation of mesogens is restricted by crowding at the nanoparticle surface. Samples of unbound polymer were also prepared and exhibited similar transition behavior.
X-ray diffraction study of crystallite size-distribution and strain in carbon blacks
Authors: Ungár T. , Gubicza J. , Ribárik G. , Zerda T. W. 
Published: April 2011

ABSTRACTThe crystallite size and size-distribution in carbon blacks in the presence of strain are determined by recently developed procedure of X-ray diffraction peak profile analysis. The Fourier coefficients of the measured physical profiles are fitted by Fourier coefficients of well established ab initio functions of size and strain peak profiles. Strain anisotropy is accounted for by expressing the mean square strain in terms of average dislocation contrast factors. Crystallite shape anisotropy is modelled by ellipsoids incorporated into the size profile function. To make the fitting procedure faster, the Fourier transform of the size profile is given as an analitical function. The method is applied to carbon blacks treated at different preassures and temperatures. The microstructure is characterised in terms of crystallite size distribution, dislocation density, and crystallite shape anisotropy.
Carbon Coated Silica For Elastomer Reinforcement
Authors: Kohls D. , Beaucage G. , Pratsinis S.E. , Kammler H. , Skillas G. 
Published: April 2011

ABSTRACTCarbon coated silica made by flame synthesis was investigated for reinforcement of styrene-butadiene (SBR) rubber. These composite silica/carbon fillers were examined through small angle x-ray scattering (SAXS), TEM, and AFM showing that these fillers have a rough fractal surface and have fractal aggregate structures. The carbon coated silica fillers were compounded with elastomers and their effect on reinforcement was measured using dynamic mechanical analysis and tensile testing. These fillers were also compared to commercial fumed silica, carbon black, and carbon black/silica composite fillers.