bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrodeposition of Metals on Conductive Polymer Films
Authors: Hepel Maria , Adams Laura , Rice-Belrose Cynthia 
Published: June 2019

ABSTRACTThe electrodeposition of copper on composite conductive polymer polypyrrole/polystyrenesulfonate PPy(PSS) has been studied. The morphology of copper deposits was investigated in the presence of thiourea and other additives. It has been found that in the presence of thiourea in the solution, the rate of copper deposition on a PPy(PSS) substrate is slightly inhibited but the rate of copper stripping is faster than in its absence. The Electrochemical Quartz Crystal Microbalance (EQCM) technique allowed us to simultaneously monitor voltamperometric and resonance frequency vs. potential or time characteristics. The amount of electrodeposited copper was controlled by monitoring the EQCM resonant frequency. Composite PPy(PSS) films functioning as cation-exchange membranes were used as substrate materials for metal deposition. They allowed us to electrodeposit copper not only on the surface of the conductive polymer but also inside the polymer matrix. The size of copper nanocrystals formed inside the polymer was controlled by the applied electrode potential. Copper crystals as small as 20 nm were detected with Transmission Electron Microscopy (TEM).
Open Air Fabrication of Al2O3 Thin Films at Room Temperature
Authors: Okamoto T. , Toyoda K. , Murahara M. 
Published: June 2019

ABSTRACTA thin layer of water or hydrogen peroxide solution, which was formed on a pure aluminum substrate, was photodissociated by ArF excimer laser( λ =193nm) or Xe2* excimer lamp (λ = 172nm) light to photochemically oxidize the surface of aluminum substrate. The layer was formed by a capillary phenomenon between the substrate and a fused silica glass as an entrance window of ultraviolet light. Then, the layer was photodissociated by the excimer laser or the excimer lamp light irradiation to generate active oxygen; the surface oxidization was performed by the photo-induced active oxygen. The surface before and after modification was evaluated by the XPS analysis; the high densed photo-oxidization film was confirmed on the modified surface, compared with a natural oxidization film Furthermore, the contact angle with water became remarkably small, and it is seen that the treated surface was quite densely oxidized.
Halide Electroadsorption on Single Crystal Surfaces
Authors: Ocko B. M. , Wandlowski Th. 
Published: June 2019

ABSTRACTThe structure and phase behavior of halides have been investigated on single crystals of Ag and Au using synchrotron x-ray scattering techniques. The adlayer coverages are potential dependent. For all halides studied we found that with increasing potential, at a critical potential, a disordered adlayer transforms into an ordered structure. Often these ordered phases are incommensurate and exhibit potential-dependent lateral separations (electrocom-pression). We have analyzed the electrocompression in terms of a model which includes lateral interactions and partial charge. A continuous compression is not observed for Br on Ag(100). Rather, we find that the adsorption is site-specific (lattice gas) in both the ordered and disordered phases. The coverage increases with increasing potential and at a critical potential the disordered phase transforms to a well-ordered commensurate structure.
Electrochemical Reactions of Molybdenum Nitride Electrodes in H2SO4 Electrolyte
Authors: Roberson S. L. , Finello D. , Davis R. F. 
Published: June 2019

ABSTRACTThe electrochemical reaction of polycrystalline MoxN (x=1 or 2) thin film electrodes in 4.4 M H2SO4 electrolyte has been investigated. The films were prepared by a temperature programmed procedure involving the reaction of MoO3, and NH3 The electrochemical voltage stability of these films in the electrolyte, referenced to a standard hydrogen electrode (SHE), was + 0.70 V (-0.01 to + 0.69). Below + 0.69 V, cyclic voltammetry and AC impedance spectroscopy indicated that MoxN electrodes were capacitive. However, above this value an electrochemical reaction of the MoxN films was observed. The formation of an amorphous phase in the reacted MoxN films was indicated by X-ray diffraction (XRD) patterns. Secondary ion mass spectroscopy (SIMS) detected the presence of hydrogen, oxygen, and sulfur. The voltage bias (+ or -) applied to the electrodes influenced the chemical composition of the reacted MoxN films.
The Effects of Carbonate-Bicarbonate Concentration on Empirical Corrosion Diagram of Mild Steel as a Material of Geological Disposal Package for High Level Nuclear Wastes
Authors: Nakayama Guen , Fukaya Yuichi , Akashi Masatsune 
Published: June 2019

ABSTRACTIn the scheme for geological disposal of high level radioactive nuclear wastes, the burial pit is to be isolated from the sphere of human life by a multiple-barrier system, which consists of an artificial barrier, composed of a canister, an overpack and a bentonite cushioning layer, and a natural barrier, which is essentially the bedrock. As the greatest as well as essentially the sole detriment to its integrity would be corrosion by groundwater. The groundwater comes to it seeping through the bentonite zone, thereby attaining conceivably the pH of transition from general corrosion to passivity, pHd, the behaviors of mild steel in such a groundwater environment have been examined. It has been shown that the pHd is lowered (enlargement of the passivity domain) with rising temperature and carbonate-bicarbonate concentration, while it is raised (enlargement of the general corrosion region) with increasing concentrations of chloride and sulfate ions.
Nanofabricated SiO2-Si-SiO2 Resonant Tunneling Diodes
Authors: Fleming J. G. , Chow E. , Lin S.-Y. 
Published: June 2019

ABSTRACTResonance Tunneling Diodes (RTDs) are devices that can demonstrate very highspeed operation. Typically they have been fabricated using epitaxial techniques and materials not consistent with standard commercial integrated circuits. We report here the first demonstration of SiO2-Si-SiO2 RTDs. These new structures were fabricated using novel combinations of silicon integrated circuit processes.
Electronic and Magnetic Properties of d1 Pnictide-Oxides: Na2Ti2Pn2O (Pn = As, Sb)
Authors: Ozawa Tadashi C. , Bieringer Mario , Greedan John E. , Kauzlarich Susan. M. 
Published: June 2019

ABSTRACTBulk physical properties of layered pnictide-oxides, Na2Ti2Pn2O (Pn = As, Sb) have been characterized. Both As and Sb compounds exhibit anomalous transitions in temperature dependent magnetic susceptibility and electrical resistivity. The powder neutron diffraction data show no superlattice reflections indicative of long-range order. The origin of the physical property anomalies and structure-property relationship between As and Sb compounds are described in terms of a charge-density-wave/spin-density-wave mechanism.
Electronic, Magnetic and Structural Properties of the RFeO3 Antiferromagnetic-Perovskites at Very High Pressures
Authors: Pasternak Moshe P. , Xu W. M. , Rozenberg G. Kh. , Taylor R. D. 
Published: June 2019

AbstractAt ambient pressure the orthorhombic perovskites R-orthoferrites (R Ξ Lu, Eu, Y, Pr, and La) exhibit very large optical gaps. These large- gap Mott insulators in which the 3d5 high-spin ferric ions carry large local moments and magnetically order at TN > 600 K, undergo a sluggish structural first-order phase transition in the 30-50 GPa range, with the exception of the LuFeO3 which undergoes an isostructural volume reduction resulting from a high to low-spin crossover. High-pressure methods to 170 GPa using Mossbauer spectroscopy, resistance, and synchrotronbased XRD in diamond anvil cells were applied. Following the quasi-isostructural volume reduction (3-5%) the new phase the magnetic-ordering temperature is drastically reduced, to ∼ 100 K, the direct and super-exchange interactions are drastically weakened, and the charge-transfer gap is substantially reduced. The high-pressure (HP) phases of the La and Pr oxides, at their inception, are composed of high- and low-spin Fe3+ magnetic sublattices, the abundance of the latter increasing with pressure but HP phases of the Eu, Y, and Lu oxides consist solely of low-spin Fe3+. Resistance and Mössbauer studies in La and Pr orthoferrites reveal the onset of a metallic state with moments starting at P > 120 GPa. Based on the magnetic and electrical data of the latter species, a Mott phase diagram was established.
Three Dimensional Structure of UMo8O26: Ordering of U-Vacancies
Authors: Zakharov N.D. , Werner P. 
Published: June 2019

AbstractThe structure and composition of UMo8O26 synthesized by solid state reaction method have been investigated by High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction, and EDX microanalysis. The ordering of U vacancies results in considerable enlargement of unit cell parameters: an=6.44 nm, bn=1.45 nm, cn=1.6 nm. It is build up of four layers piled up in c direction. Each following layer is shifted relative to previous one by vector bn/4. Eight hexagonal tunnels in each layer are filled by U atoms, while the eight others are vacant (V). Interaction between U cations and vacancies is driving force for ordering. The variation of stoichiometry can be a reason for appearance of incommensurate modulations in these crystals. It seems plausible that this structure might also exhibit superconductivity at low temperatures.
First-Principles Calculation of the Orbital Magnetic Moment of O and Cr in Half-metallic CrO2
Authors: Jeng Horng-Tay , Guo G. Y. 
Published: June 2019

AbstractThe electronic and magnetic properties of half-metallic CrO2 have been studied by using the full-potential linearized muffin-tin orbital method within the local spin-density approximation (LSDA)+U approach. It is found that the orbital magnetic moment of Cr atom is quenched while O atom exhibit relatively significant orbital moment in CrO2. For the Hubbard U of 3 eV, LSDA+U gives the orbital moment of -0.051μB/atom for Cr and -0.0025μB/atom for O, being in good agreement with the experimental orbital moments of -0.05 for Cr and -0.003μB/atom for O, respectively. In contrast, LSDA gives the orbital moment of -0.037 for Cr and -0.0011 μB/atom for O, being too small as compared with the magnetic circular dichroism measurements. For the larger U considered in this work, both spin and orbital moments almost increase linearly with respect to U.
Synthesis and Structural Characterization of Sol-Gel Derived Barium Zirconium Titanate Thin Films
Authors: Dixit A. , Savvinov A. , Majumder S.B. , Guo R.S. Katiyar R. , Bhalla A.S. 
Published: June 2019

AbstractBarium zirconium titanate (BZT) thin films are attractive candidates for dynamic random access memories and tunable microwave devices. In the present work a wide range of Zr doped BaTiO3 thin films have been prepared by sol-gel technique. X-ray diffraction and micro-Raman scattering studies confirmed the structural phases in the powder and film of BZT and various structural transitions of BaTiO3 as a function of different Zr content compared well with the published result on ceramics and single crystalline BZT. The deposited films had smooth, crackfree and homogeneous microstructure and Zr content has strong influence on the evolution of the microstructures of the films. Some selected compositions of these films were characterized in terms of their dielectric properties and phase transition behavior. BZT film with 20 at % Zr had a ferroelectric to paraelectric transition in the vicinity of room temperature. Efforts are underway to optimize the annealing condition and grow epitaxial BZT films, with various Zr contents, on a suitable single-crystalline substrate.
New Layered Manganese Oxychlorides
Authors: Knee Christopher S. , Weller Mark T. 
Published: June 2019

AbstractThe synthesis, structure and preliminary magnetic characteristics of the new layered manganese oxide chlorides, Sr2MnO3Cl and Sr4Mn3O8-yCl2 are reported. Sr2MnO3Cl adopts a K2NiF4 type structure with sheets of MnO5 square based pyramids linked through oxygen and separated by SrCl layers; it is the end member of a new family of Ruddlesden-Popper type manganese oxide halides which includes the 3-layer member Sr4Mn3O8-yCl2. Magnetic susceptibility measurements reveal antiferromagnetic transitions at 95 K and 90 K for Sr2MnO3Cl and Sr4Mn3O8-yCl2 respectively. These materials demonstrate the extension of mixed anion chemistry to manganese and will increase flexibility in designing and controlling oxidation states of new GMR materials.
Synthesis, Structures, and Physical Properties of Yttrium-Doped Strontium Manganese Oxide Films
Authors: Francis Andrew J. , Salvador Paul A. 
Published: June 2019

AbstractCubic strontium manganese oxide is an end-member of the colossal magnetoresistive (CMR) family of manganese-based perovskites, Ln1-xAExMnO3. Because normal synthesis conditions lead to the 4-H hexagonal polymorph, high-pressure conditions are typically used to obtain the cubic perovskite polymorph. In this work, we describe the synthesis and structural/physical characterization of the cubic perovskite form of the high-alkaline-earth containing phases of Y1-xSrxMnO3 (x ≥ 0.7) as epitaxial thin films. Thin films of various stoichiometries were grown on single-crystal perovskite substrates SrTiO3, NdGaO3, and LaAlO3 using pulsed laser deposition. After optimizing deposition conditions, the perovskite polymorph is obtained using PLD at 800°C and 10-100 mTorr O2 for x=1, 0.9, 0.8, and 0.7, as demonstrated by x-ray diffraction. Epitaxial growth was determined to be cube-on-cube. Electrical property measurements demonstrated insulating behavior and no metal-insulator transition or magnetoresistive behavior, similar to related stable compounds.
Quantitative HRTEM investigation of an obtuse angle dislocation reaction in gold with a CScorrected field emission microscope
Authors: Jinschek Joerg R. , Kisielowski Ch. , Radetic T. , Dahmen U. , Lentzen M. , Thust A. , Urban K. 
Published: June 2019

AbstractWe investigate quantitatively the non periodic arrangement of atom columns surrounding an obtuse angle dislocation reaction in gold utilizing a CM200 FEG instrument equipped with a spherical aberration corrector. The in-plane component of the Burgers vector of the observed stair-rod dislocation is ⅙ [110]. Column positions are determined from single lattice images and compared with those from a reconstructed electron exit wave. We find that absolute position measurements of 1–3 pm require knowledge of the defocus to better than 1 nm which can be achieved by a reconstruction of the exit-plane wave. In contrast, a defocus value of 8.9 nm already leads to apparent displacements as large as 35 pm if single lattice images are considered. Such discrepancies are either caused by residual lens aberrations or by the superposition of delocalization effects at interfaces caused by defocusing of the objective lens. Commonly, however, only relative displacements are of interest. In this case the CS corrector improves the interpretability of single defocused lattice images with a remarkable signal to noise ratio which is advantageous for in-situ experiments. As an example for analyzing in-situ experiments we determine displacements recorded in a time resolved experiment of radiation induced atom motion on surfaces.
Nanometer Scale Composition Variations in Ge Quantum Dots on Si(100)
Authors: Zhang Yangting , Floyd Margaret , Drucker Jeff , Crozier P.A. , Smith David J. , Driver K.P. 
Published: June 2019

AbstractElectron-energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) was used to measure nm-scale composition variations in Ge/Si(100) islands grown by molecular beam epitaxy (MBE) at substrate temperatures 400°C ≤T ≤700°C and a growth rate of 1.4 ML/min (1 monolayer, ML=6.78x1014 atoms / cm2). These measurements were correlated with island ensemble morphology determined by atomic force microscopy (AFM). The average Si concentration of the islands and Si/Ge interface width increased monotonically with growth temperature. Integrated island volumes measured by AFM were proportional to the equivalent Ge coverage, øGe, with slopes greater than one for the higher deposition temperatures. This result confirms that the islands grow faster than the Ge deposition rate. Linear behavior of the island volume vs. øGe curves implies that the average Ge composition is independent of island size. The volume at which islands change shape from pyramids to domes correlates well with the average Ge content of the islands in the context of simple strain-scaling arguments. For T=700°C, rapid Si interdiffusion precludes formation of pure Ge pyramids for growth at 1.4 ML/min. Growth at 4.8 ML/min kinetically stabilizes pure Ge pyramid clusters, allowing their formation prior to Si interdiffusion.
“Hairy Tube” Polymer Templates From Diblock Copolymer Thin Films
Authors: Tokarev Igor , Minko Sergiy , Stamm Manfred 
Published: June 2019

AbstractWe report about the fabrication of polymeric nanotemplates for the fabrication of regular arrays of nanocylindrical domains. Using combi-like macromolecules obtained by complexation of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymer with a low molecular weight surfactant pentadecylphenol (PDP) we prepared thin polymer films deposited on a neutral substrate. The block-copolymer – PDP complex segregates into cylindrical morphology formed by P4VP-PDP fragments. The PDP molecules were easily removed by selective solvent (methanol) after annealing of the film. The resulting morphology consists of cylindrical channels of 7-8 nm in diameter oriented perpendicular to the substrate and regular packed in the hexagonal lattice with the period of 21 nm. Dry plasma etching, Atomic Force Microscopy (AFM), and Grazing Incidence Small Angle X-ray Scattering (GISAXS) were employed to characterize the films.
Synthesis and Characterization of Self-Assembled Piezoelectric ZnO Nanostructures and Integration with Si Processing
Authors: Cresce A. V. , Ali H. A. , Iliadis A. A. , Lee U. , Kofinas P. 
Published: June 2019

AbstractThe formation of 10 nm self-assembled ZnO nanoparticles on Si and SiO2/Si surfaces, using diblock copolymers, and wet chemical processing compatible with semiconductor manufacturing, is reported. The diblock copolymer, consisting of norbornene and a norbornenedicarboxcylic acid blocks with a 400 to 50 repeat unit ratio, was synthesized by ring opening metathesis polymerization. The microphase separation of the block copolymer was employed to grow spherical self-assembled ZnO nanoparticles The self-assembly of the inorganic nanoparticles was achieved at room temperature in the liquid phase by incorporating ZnCl2 to the carboxylic acid block, or by exposure of a solid film to diethyl zinc vapors. Subsequent room temperature wet chemical processing of the doped films resulted in the formation of zinc oxide, followed by the saturation of double bonds in the polymer backbone. The formation of ZnO was verified by x-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM ) micrographs show the size and distribution of the zinc oxide nanoclusters in the polymer matrix. This study provided information on the formation of zinc oxide structures in a self-assembled polymer matrix, with the intention of controlling the shape and distribution of zinc oxide domains. The doped diblock copolymer was applied on Si and SiO2/Si wafers, by standard spinon techniques, and its photolithographic patterning metalization was developed.
Manipulation of Germanium Nanocrystals in a Tri-Layer Insulator Structure of a Metal-Insulator-Semiconductor Memory Device
Authors: Teo L.W. , Heng C.L. , Ho V. , Tay M. , Choi W.K. , Chim W.K. , Antoniadis D.A. , Fitzgerald E.A. 
Published: June 2019

AbstractA metal-insulator-semiconductor (MIS) device that consists of germanium (Ge) nanocrystals embedded in a novel tri-layer insulator structure is proposed for memory applications [1]. The tri-layer structure comprises a thin (≈5nm) rapid thermal oxidation (RTO) silicon dioxide (SiO2) layer, a Ge+SiO2 middle layer (6 - 20 nm) deposited by RF co-sputtering technique and a RF-sputtered silicon dioxide capping layer. High-resolution transmission electron microscopy (HRTEM) results show that Ge nanocrystals of sizes ranging from 6 –20 nm were found after rapid thermal annealing of the trilayer structure at 1000°C for 300s. The electrical properties of these devices have been characterized using capacitance versus voltage (C-V) measurements. A significant hysteresis was observed in the C-V curves of these devices, indicating charge trapping in the composite insulator. Comparison with devices having similar tri-layer insulator structure, but with a pure sputtered oxide middle layer (i.e. minus the Ge nanocrystals), clearly indicated that the observed charge trapping is due to the presence of the Ge nanocrystals in the middle layer. The C-V measurements of devices without the capping SiO2 layer exhibited no significant hysteresis as compared to the embedded Ge nanocrystal tri-layer devices. The HRTEM micrographs showed that the presence of the capping oxide is critical in the formation of nanocrystals for this structure. By varying the thickness of the middle layer, it was found that the maximum nanocrystal size correlates well with the middle layer thickness. This indicates that the nanocrystals are well confined by the RTO oxide layer and the capping oxide layer. In addition, Ge nanocrystals formed using a thinner middle layer were found to be relatively uniform in size and distribution. This structure, therefore, offers a possibility of fabricating memory devices with controllable Ge nanocrystals size.
Laser Guidance Deposition Technique for Patterning Microstructures Made of Nanoparticles with Varying Surface Functionality
Authors: Xu Juntao , Zhou Changgong , Grant Sheila , Nadgorny Edward , Drelich Jaroslaw 
Published: June 2019

AbstractWe present results on patterning microstructures using laser-guidance deposition of nanoparticles from particle-in-solvent suspensions. A laser beam axially confines and propels the particles inside a hollow optical fiber towards a substrate. Confining is provided by the gradient forces arising from light refraction or electrical forces on polarizable particles. The driving force results from the momentum conservation of photons scattered on particles. Polystyrene particles (100 and 400 nm in diameter) and gold particles (from 8 to 50 nm) with different surface organic functionality serve as a constructive material for fabrication of microstrips. In the experiments, the laser power varies from 0.1 to 1.6 W. The microstrips produced under different deposition conditions are studied using optical microscopy and atomic force microscopy. It was found that deposited polystyrene and gold particles form nanoclusters consisting of at least several particles. If deposited at an appropriate rate, such nanoclusters form multilayer microstrips of high particle density. The typical width of the microstrips ranges from less than 10 microns to 100 microns. This technique allows us to fabricate parallel arrays made of colloidal particles with different surface functionality, which seems to be an especially attractive approach for developing novel chemical and biological microsensors.
Carbon Nanotube Deposition using Helicon Plasma CVD at Low Temperature
Authors: Muroyama Masakazu , Yagi Takao , Inoue Kouji , Saito Ichiro 
Published: June 2019

AbstractWe developed a novel growth method of aligned carbon nanotubes. Aligned carbon nanotubes are grown on a metal catalyst on a glass substrate using biased Helicon plasma chemical vapor deposition (HPECVD) of CH4/H2 gases from 400 C to 500 C. The Helicon plasma source is one of the high-density plasma sources and is promising for low temperature carbon deposition. A Ni film was used as a catalyst to reduce the activation energy of the nanotubes' growth. The carbon nanotubes were deposited on the nickel catalysis layer selectively.