bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterizations of Core-Shell Nanoparticle Catalysts for Methanol Electrooxidation
Authors: Maye Mathew M. , Luo Jin , Chan Wai-Ben , Han Li , Kariuki Nancy , Naslund H. Richard , Engelhard Mark H. , Lin Yuehe , Sze Randoll , Zhong Chuan-Jian 
Published: April 2011

ABSTRACTThis paper describes the results of an investigation of the structure and composition of core-shell gold and alloy nanoparticles as catalytically active nanomaterials for potential fuel cell catalysis. Centered on the electrocatalytic methanol oxidation, we show three sets of results based on electrochemical, surface, and composition characterizations. First, electrochemical studies have revealed that the nanostructured catalysts are active towards the electrooxidation of methanol and carbon monoxide. Second, X-ray photoelectron spectroscopy (XPS) data have shown that the organic encapsulating shells can be effectively removed electrochemically or thermally, which involves the formation of oxides on the nanocrystals. Thirdly, direct current plasma - atomic emission spectrometry (DCP-AES) has revealed insights for the correlation of the composition of alloy nanoparticles with the catalytic activities. Implications of these results to the design of nanostructured catalysts will also be discussed.
Effective Hydrogen Separation Using Ion Beam Modified Polymeric Membranes
Authors: Coleman M. R. , Xu X. , Ilconich J. , Ritchie J. , Hu L. 
Published: April 2011

ABSTRACTHigh purity H2 gas streams are increasingly important for a variety of applications including feed gases for fuel cells. The potential of hydrogen gas as primary energy source has generated considerable interest in hydrogen separation technologies. We have been investigating ion beam irradiation as a method to modify polymeric membranes to enhance both hydrogen permeability and permselectivities. Combined high permeabilities and permselectivities are required to give high recoveries of high purity hydrogen. Ion irradiation typically results in the formation of numerous crosslinks within the polymer matrix that should enable these materials to maintain selectivities at high temperatures and to resist chemical attack. Helium separations over a range of temperatures of irradiated polyimides were used as a model of the hydrogen system. Finally, the impact of irradiation conditions on gas separations in these materials will be addressed.
Spontaneous spirals in vibrated granular chains
Authors: Ecke R. E. , Daya Z. A. , Rivera M. K. , Ben-Naim E. 
Published: April 2011

We present experimental measurements on the spontaneous formation of compact spiral structures in vertically-vibrated granular chains. Under weak vibration, when the chain is quasi two-dimensional and self-avoiding, spiral structures emerge from generic initial configurations. We compare geometrical characteristics of the spiral with that of an ideal tight spiral. Globally, the spiral undergoes a slow rotation such that to keep itself wound, while internally, fast vibrational modes are excited along the backbone with transverse oscillations dominating over longitudinal ones. Spirals have an extremely small volume in phase space, and hence, their formation demonstrates how nonequilibrium dynamics can result in a nonuniform sampling of phase space.PACS numbers: 81.05.Rm, 83.10Nn
Using Interdisciplinary Examples in Nanotechnology to Teach Concepts of Materials Science and Engineering
Authors: Crone Wendy C. , Payne Amy C. , Zenner Greta M. , Ellis Arthur B. , Lisensky George C. , Condren S. Michael , Lux Ken W. 
Published: April 2011

ABSTRACTThe National Science Foundation-supported Materials Research Science and Engineering Center (MRSEC) on Nanostructured Materials and Interfaces at the University of Wisconsin – Madison has an extensive education and outreach effort. One theme of this effort is the development of instructional materials based on cutting-edge research in nanoscale science and engineering. The Nanoworld Cineplex contains movies and demonstrations that can be brought into classes, and the Nanotechnology Lab Manual contains numerous experiments that can be used for virtual or actual laboratories. Also available are kits, software, teaching modules and articles. A hands-on kit for nontechnical audiences, “Exploring the Nanoworld,” has been produced in collaboration with the Institute for Chemical Education.In this paper, novel hands-on demonstrations and innovative laboratory experiments aimed at the college level will be highlighted. High-tech devices and materials such as light emitting diodes (LEDs), shape memory alloys, amorphous metal, and ferrofluids are discussed in the classroom and studied in the laboratory as illustrations of nanotechnology and its impact on energy, the environment and our quality of life. These examples illustrate interdisciplinary research that provides connections among materials science, chemistry, physics, engineering, and the life sciences. They also highlight the tools of nanotechnology, such as scanning probe microscopy, electron microscopy, x-ray diffraction, and chemical vapor deposition, which are associated with the preparation and characterization of nanostructured materials. Demonstrations of the incorporation of nanotechnology to teach fundamental materials science principles presented are summarized at http://www.mrsec.wisc.edu/edetc.
PUI/MRSEC Collaboration to Create Opportunities for Women in Materials-Research
Authors: Goldberg Velda , Kaplan Michael , Soltzberg Leonard 
Published: April 2011

ABSTRACTThis three-year collaboration between a predominately undergraduate women's college (Simmons College) and a NSF-supported Materials Research Science and Engineering Center (the Cornell Center for Materials Research (CCMR)) focuses on establishing a collaborative Simmons/Cornell research program that provides opportunities for students to work with faculty on timely research projects, have access to sophisticated instrumentation, and gain related work experience in industrial settings. To interest women in participating in materials-related research and to encourage them to consider further career exploration in this area, the secondary goal of the project focuses on augmenting women's undergraduate experience. In this regard, the project uses the PUI/MRSEC collaboration to enhance the undergraduate curriculum at Simmons and encourage new Ph.D.s in materials-related disciplines at Cornell to consider academic careers at Primarily Undergraduate Institutions (PUIs).To provide opportunities for students to work on research throughout their undergraduate careers, this program focuses on studying the degradation processes in organic light emitting diodes (OLEDs). These materials are currently of great interest for display applications, and an understanding and control of the degradation processes could ultimately influence their use in various types of consumer products.To widen science students' exposure to materials science, a new minor in materials was developed and materials science topics are being incorporated into physics and chemistry courses. To encourage students to consider graduate or industrial careers in materials science and to ease the transition into these large research environments, CCMR will place students in summer industrial jobs and REU positions. To provide students with further access to sophisticated instrumentation, a portion of the laboratory requirement for the new minor in materials will be co-taught during the summer by Simmons and Cornell collaborators at CCMR's Shared Experimental Facilities. Cornell's graduate students will participate in the program as mentors for Simmons undergraduates and will visit Simmons to better understand postgraduate teaching careers at PUIs.
Assembly of Gold Nanoparticles on DNA Strands
Authors: Noyong Michael , Gloddek Kirsten , Simon Ulrich 
Published: April 2011

ABSTRACTIn this work we report first results on a direct deposition of 2–4nm gold nanoparticles onto DNA strands. In a two step protocol first cis-Pt (cis-diamminedichloroplatinum(II), cis-Pt(NH3)2Cl2) is intercalated into a DNA duplex. In a second step cysteamine stabilized gold nanoparticles are immobilized on DNA due to a ligand exchange (NH3 vs. NH2-R) at the Pt center which was done in solution as well as on surface bound oligonucleotides. The DNA-nanoparticle assemblies are prepared on mica and silicon and are imaged by AFM.
Low Sintering Temperature of CuO-Fluxed Ag(Nb, Ta)O3 Dielectric Ceramics
Authors: Wang Chiping , Shrout Thomas , Yang Gaiying , Kim Hyo-Tae , Kwon Do-Kyun , Lanagan Michael T. 
Published: April 2011

ABSTRACTSolid solutions in the Ag(NbxTa1−x)O3 (where 0 ≤ × ≤ 1) system exhibit excellent dielectric properties at microwave frequency including high dielectric constant (200<k<400), low loss (tanΔ ∼ 0.004) and a composition controlled temperature coefficient of capacitance (TCC). For Ta-rich and Nb-rich solid solutions, the TCC values are negative and positive, respectively, and two-phase mixtures provided an average TCC close to zero. Series, parallel, and logarithmic mixing rules were applied to predict dielectric constant and TCC of polyphase assemblages (45wt%Ag(Nb0.65Ta0.35)O3+55wt% Ag(Nb0.35Ta0.65)O3) yielded an average dielectric constant of 450 and a TCC of 180ppm/°C. Microstructure analysis revealed that a CuO-rich liquid remains at the grain boundary and transmission electron microscopy shows that the CuO resides at triple points. Ag(NbxTa1−x)O3 ceramics were successfully integrated into LTCC for embedded capacitors. The addition of CuO lowered the sintering temperature to below 900°C and a low TCC was maintained for fine grained microstructures.
Cu-Compatible Ultra-High Permittivity Dielectrics for Embedded Passive Components
Authors: Ihlefeld Jon F. , Kingon Angus I. , Borland William , Maria Jon-Paul 
Published: April 2011

ABSTRACTBarium titanate thin films have been prepared by chemical solution deposition on 18 μm thick, industry standard copper foils in the absence of chemical barrier layers. The final embodiment exhibits randomly oriented BaTiO3 grains with diameters between 0.1 and 0.2 μm, and an equiaxed morphology. The average film thickness is 0.6 μm and high resolution cross sectional microscopy shows no indication of interfacial phases. The BaTiO3 films are sintered in a high temperature reductive atmosphere such that copper oxidation is avoided. Subsequent lower-temperature, higher oxygen pressure anneals are used to minimize oxygen point defects. Permittivities greater than 3000 are observed, with loss tangents under 2.5%. The BaTiO3 phase exhibits pronounced ferroelectric switching and coercive field values near 20 kV/cm. Temperature dependent measurements indicate a ferroelectric transition near 100 °C with very diffuse character. Combining the approaches of the multilayer capacitor industry with traditional solution processed thin films has allowed pure barium titanate to be integrated with copper. The high sintering temperature – as compared to typical film processing – provides for large grained films and properties consistent with well-prepared ceramics. Integrating BaTiO3 films on copper foil represents an important step towards high capacitance density embedded passive components.
Improvement of Tantalum Pentoxide Metal-Insulator-Metal Capacitors For SiGe RF-BiCMOS Technology
Authors: Sun Hongjiang , Lau Ka Man , Aksen Eyup , Bell Nancy 
Published: April 2011

AbstractImprovement activities were made in fully integrated Metal-Insulator-Metal (MIM) capacitors (>5fF/μm2) used in the advanced SiGe RF BiCMOS technology. By changing the process sequence of the lower metal electrode and the MIM capacitor, an improved MIM capacitor has achieved a lower leakage density with a better voltage linearity at 27°C − 150°C temperature range and a lower temperature dependency from −6V to +6V. Voltage coefficients VC1 and VC2 are 187ppm/V and 24ppm/V2 respectively, and temperature coefficient of capacitance TC1 is 99 ppm/°C with a negligible TC2. The leakage current density is 3.1×10−3 A/cm2 at 125°C for 5.5V with a breakdown voltage of 20V.To increase capacitance density while maintaining low leakage, an ozone treatment after tantalum pentoxide film deposition has been investigated. A capacitance density as high as 10.3fF/μm2 has been achieved with a leakage density one order lower than the standard process. The fact that the extracted dielectric constant increased from 28 to 32 as well as the significant changes of the voltage and temperature coefficients clearly indicated that the ozone treatment has changed the intrinsic property of the tantalum pentoxide film as well as the top dielectric surface.
Preparation and Use of Chip Capacitors in Ultra-Dense Multi-Chip Modules
Authors: Pryputniewicz D. , Kondoleon C. , Haley J. , Marinis T. 
Published: April 2011

ABSTRACTDraper Laboratory designs and produces ultra-dense multi-chip modules that achieve an integration density, which is only exceeded by that of custom ASIC chips. These modules are fabricated by tiling an adhesive coated substrate with bare integrated circuit chips and passive components that are thinned to 150 microns thick. Multiple layers of thin film copper conductors, supported on Kapton film dielectric, are used to route signals between these components. Connections to their I/O pads and between signal layers are made through laser drilled vias, which are copper plated. The various types of capacitors used in modules for RF applications present several fabrication challenges. In comparison to active IC devices, capacitors have wider dimensional tolerances, are more easily damaged by mechanical handling, and are more susceptible to damage during laser drilling of vias. This paper will discuss these issues and the approaches that have been taken to address them.
Crystallization of Sub-100 nm-Thick Bi4-xLaxTi3O12 Films on Silicon Substrates and Their Electrical Properties
Authors: Kohno Atsushi , Ishitsu Fumitake , Matuo Kazuhiro , Tomari Hiroyuki 
Published: April 2011

ABSTRACTPolycrystalline Bi4-xLaxTi3O12 (BLT) thin films were formed on p-Si(100) substrates. Crystallization of the film was investigated quantitatively by X-ray diffraction (XRD) and X-ray reflection (XRR) analyses. The film was crystallized onto bismuth-oxide layered perovskite structure when annealing temperatures became higher than 550°C. The annealing time dependence of diffraction intensity and peak width indicated that grain growth occurred during crystallization. Moreover, it was shown that the average crystal dimension in the BLT film reached ca. 60 nm by 120-min annealing. That value is comparable to the B LT thickness. Film thickness and density were evaluated by XRR analysis. Simulation fitting showed that the BLT film was densified and that an interfacial layer was formed during crystallization. Pole figure measurements also suggested that the c-axis of B LT was preferentially oriented to nearly parallel the surface. Clockwise hysteresis loops were observed at room temperature in capacitance-voltage (C-V) characteristics of Au/BLT/p-Si structures. The coercive field and the dielectric constant of 65 nm-thick BLT films crystallized at 550°C for 60 min were evaluated to be ca. 23 kV/cm and ca. 17, respectively.
Ferroelectric property of an epitaxial lead zirconate titanate thin film deposited by a hydrothermal method
Authors: Morita Takeshi , Wagatsuma Yasuo , Cho Yasuo , Morioka Hitoshi , Funakubo Hiroshi , Nava Setter 
Published: April 2011

ABSTRACTHydrothermal method has various advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure and a large thickness. Although epitaxial PZT thin film deposition has reported, ferroelectric measurement has not been conducted due to the peel-off morphology of the film. The present paper investigates the improvement of an epitaxial PZT thin film deposited via a hydrothermal method. By adjusting the position at which the substrate was suspended in the solution, smooth morphology surface was successfully obtained. As a bottom electrode, 200 nm SrRuO3 thin film was deposited on SrTiO3 single crystals, and the PZT thin was deposited on SrRuO3. The remanent polarization 2Pr for PZT on SrRuO3/SrTiO3 (001) was 19.5 μC/cm2 and that of PZT on SrRuO3/SrTiO3 (111) was 37.2 μC/cm2 respectively. The self alignment poling direction was confirmed via scanning nonlinear dielectric microscopy and is thought to have been related to the deposition mechanisms.
Hydrothermally Deposited PZT Thin Films With Vertically Oriented Columnar Growth
Authors: Solberg Scott , Rodkin Alexandra , Xu Baomin , Littau Karl 
Published: April 2011

ABSTRACTA novel growth mode for hydrothermal films of lead zirconate titanate (PZT) has been discovered. Previously reported hydrothermal PZT films have had a loosely-packed cubic morphology, and indeed that is the most common growth mode. However, under special growth conditions, with much more dilute reagent concentrations than previously reported, substantially vertically oriented, long rod shaped grains may be grown. Metal-organic reagents such as lead acetate trihydrate, zirconium propoxide, and titanium isopropoxide were used along with potassium hydroxide mineralizer. Metal and metal-coated substrates with appropriate perovskite seed layers, such as lead titanate (PT) and PZT were used. Unlike other film deposition methods, such as sputtering, MOCVD, or sol-gel, which typically require greater than 500°C processing temperatures, the hydrothermal processes described in this report allowed the growth of highly crystalline films at temperatures as low as 120°C. The unique vertical rod-like ferroelectric films may be useful in electrical devices such as capacitors.
First Prototype of High-Density Ferroelectric Data Storage System
Authors: Hiranaga Yoshiomi , Cho Yasuo , Wagatsuma Yasuo 
Published: April 2011

ABSTRACTThe first prototype of high-density ferroelectric data storage system based on scanning nonlinear dielectric microscopy was developed in order to establish basic elemental technologies for actual read/write functions aiming for practical application. Using this system, a data transfer rate was evaluated. 9 kbps reading and 50 kbps writing were demonstrated with respect to 440 kbit/inch bit data array written on a lithium tantalate single crystal thin plate. Additionally, we considered future prospects for developing the data storage system with further fast data transfer rate.
A Transmission Electron Microscopy Study of Dislocation Substructures in PLD-grown Epitaxial Films of (Ba,Sr)TiO3 on (001) LaAlO3
Authors: Misirlioglu I. B. , Vasiliev A. L. , Aindow M. , Ramesh R. , Alpay S. P. 
Published: April 2011

ABSTRACTEpitaxial Ba0.6Sr0.4TiO3 films were grown onto (001) LaAlO3 by pulsed-laser deposition, and the dislocation structures of the films were investigated using transmission electron microscopy. Misfit dislocations with a periodicity of about 7 nm and Burgers vectors b = a<100> were observed at the interface. High densities of threading dislocations was present in the films with Burgers vector b = a<100>. The observations reveal that threading dislocations are not generated as the result of half-loop climb from the deposit surface as proposed previously, but are instead formed when misfit dislocations are forced away from the interface during island coalescence.
Magnetostriction of Field-Structured Composites
Authors: Martin James E. , Anderson Robert A. , Gulley Gerald 
Published: April 2011

ABSTRACTField-structured magnetic particle composites are an important new class of materials that have great potential as both sensors and actuators. These materials are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic fields while the resin polymerizes. If a simple uniaxial magnetic field is used, the particles will form chains, yielding composites whose magnetic susceptibility is enhanced along a single direction. A biaxial magnetic field, comprised of two orthogonal ac fields, forms particle sheets, yielding composites whose magnetic susceptibility is enhanced along two principal directions. A balanced triaxial magnetic field can be used to enhance the susceptibility in all directions, and biased heterodyned triaxial magnetic fields are especially effective for producing composites with a greatly enhanced susceptibility along a single axis. Magnetostriction is quadratic in the susceptibility, so increasing the composite susceptibility is important to developing actuators that function well at modest fields. To investigate magnetostriction in these field-structured composites we have constructed a sensitive, constant-stress apparatus capable of 1 ppm strain resolution. The sample geometry is designed to minimize demagnetizing field effects. We have demonstrated field-structured composites with nearly 10,000 ppm strain, and have shown that at large magnetic fields a structural phase transition occurs within the composite. These experimental results are compared to microscopic, self-consistent field simulations of magnetostriction in these complex, disordered materials.
ZnO Based SAW Delay Line: Thin Film Characteristics and IDT Fabrication
Authors: Hassani Farid , Ahmadi Shahrokh , Korman Can E. , Zaghloul Mona , Hullavarad Shiva , Vispute R.D. , Venkatesan T. 
Published: April 2011

AbstractZnO, a well-known piezoelectric material, is used to develop micro-scale Surface Acoustic Wave (SAW) delay line sensor. In this work, SAW delay line Devices are fabricated employing ZnO films that are deposited by RF sputtering technique. Films are characterized prior to device fabrication by X-Ray Diffraction (XRD) for film crystalline quality, UV-visible transmission spectroscopy for optical characteristics, and Atomic Force Microscopy (AFM) for surface morphology. Interdigital electrodes producing surface acoustic waves in the hundreds of MHz are developed by photolithography and metalization techniques. SAW delay line device testing, measurement and characteristics on RF sputtered ZnO films are presented and compared.
Dielectric Properties and Long-Range Structural Order in (x)Pb(In1/2Nb1/2)O3:(1-x)Pb(Mg1/3Nb2/3)O3 Relaxor Ceramics
Authors: Tai C. W. , Baba-kishi K. Z. 
Published: April 2011

ABSTRACTThe relative permittivity of (x)Pb(In1/2Nb1/2)O3:(1-x)Pb(Mg1/3Nb2/3)O3 ceramics with compositions x=0.1, 0.3 and 0.6 were found to exhibit relaxor behavior. The maximum values of the relative permittivity at 100 Hz were ∼ 6500 at -2°C, 4000 at 5°C and 3700 at 15°C for x=0.1, 0.3 and 0.6, respectively. The 1:1 structural long-range ordering and forbidden reflections were studied by transmission electron microscopy. The size of the ordered domains increased with increasing Pb(In1/2Nb1/2)O3. In addition to the superstructure reflection 1/2 1/2 1/2, the forbidden reflection 1/2 1/2 0 and streaking were observed.
Silicide Formation at HfO2/Si and ZrO2/Si Interfaces Induced by Ar+ Ion Bombardment
Authors: Lebedinskii Yu. , Zenkevich A. , Filatov D. , Antonov D. , Gushina J. , Maximov G. 
Published: April 2011

ABSTRACTThe effect of ion bombardment with Ar+ at the energy E=2.5 keV on HfO2/Si and ZrO2/Si interfaces has been investigated in situ with XPS by growing thin metal oxide layers and further ion etching them. It is shown that a silicide layer ∼2 nm in thickness is forming, and Ar+ ion beam affects MeO2/Si (Me=Hf, Zr) interface at thickness ≤3 nm. Ex situ AFM/STM corroborates the formation of silicide layer at metal oxide/silicon interface.