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Transition from streamer to Townsend mechanisms in dielectric voids

P.H.F. Morshuis、F.H. Kreuger1990-12-14Journal of Physics D Applied Physics

The time dependence of the discharge processes in dielectric bounded voids of 40 mm have been studied under power frequency voltage. Fast oscilloscopic techniques were used to observe the pulse shape of single discharges or clusters of discharges. Synchronous optical registration of discharge images was performed usin…

High voltage insulation and dielectric phenomenaPlasma Diagnostics and ApplicationsElectrowetting and Microfluidic Technologies

The effect of aluminium inclusions on the dielectric breakdown of polyethylene

R W Coppard、Jeremy Bowman、L. A. Dissado 等 5 位作者1990-12-14Journal of Physics D Applied Physics

A narrow size distribution of irregular aluminium particles was blended into power cable insulation grade polyethylene. Some batches of the resulting material were then melt-filtered to reduce the size of particles present and narrow the distributions further. The failure statistics of the loaded polymers were then de…

High voltage insulation and dielectric phenomenaPower Transformer Diagnostics and InsulationMaterial Properties and Processing

Ultraviolet laser excited luminescence of Ti-sapphire

L. E. Bausá、I. Vergara、F. Jaqué 等 4 位作者1990-12-10Journal of Physics Condensed Matter

The photoluminescence of Ti-doped sapphire (Ti:Al 2 O 3 ) crystals excited using the second (532 nm) and fourth (266 nm) harmonics of a high power pulsed Nd:YAG laser has been investigated. Excitation at 532 nm into the crystal field band of Ti 3+ produces the well known broad infrared emission band corresponding to t…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsSolid State Laser Technologies

Graphitic clusters in hydrogenated amorphous carbon induced by keV-ion irradiation

Giuseppe Compagnini、G. Fóti、R. Reitano 等 4 位作者1990-12-10Applied Physics Letters

Energy gap and hydrogen concentration have been measured in hydrogenated amorphous carbon (a-C:H) after bombardment with 100 keV He+ and 300 keV Ar+ ion beams, up to ion fluences 3×1016 ions/cm2. a-C:H films have been obtained by ion irradiation at low ion fluences of polystyrene layers and with a subsequent low-tempe…

Diamond and Carbon-based Materials ResearchIon-surface interactions and analysisPolymer Nanocomposite Synthesis and Irradiation

Metal reactivity effects on the surface recombination velocity at InP interfaces

Y. Rosenwaks、Yoram Shapira、D. Huppert1990-12-10Applied Physics Letters

Direct measurements of the surface recombination velocity (SRV) on etched InP(110) and at its interfaces with various metals deposited by thermal evaporation have been performed using ultrafast time-resolved photoluminescence. The results show that the original InP low SRV is retained when these surfaces are coverd wi…

Quantum Dots Synthesis And PropertiesSilicon Nanostructures and PhotoluminescenceSemiconductor materials and interfaces

Epitaxial ferromagnetic τ-MnAl films on GaAs

T. Sands、J. P. Harbison、M. L. Leadbeater 等 7 位作者1990-12-10Applied Physics Letters

We report the growth of epitaxial τ-MnAl ferromagnetic films on GaAs substrates by molecular beam epitaxy (MBE). Reflection high-energy electron diffraction and x-ray diffraction show that the τ-phase films grow with the c axis of the tetragonal unit cell normal to the {100}GaAs substrate surface. In the bulk, τ-MnAl…

Magnetic and transport properties of perovskites and related materialsMagnetic Properties of AlloysHeusler alloys: electronic and magnetic properties

Polymer-dispersed chiral liquid crystal color display

P. P. Crooker、Deng‐Ke Yang1990-12-10Applied Physics Letters

We describe a new type of color display consisting of polymer-dispersed droplets of chiral liquid crystal having negative dielectric anisotropy. In the field-off state, the droplets scatter light randomly. In the field-on state the droplets selectively reflect a bright color. Measurements of reflectivities and switchi…

Liquid Crystal Research AdvancementsPhotonic Crystals and ApplicationsAdvanced Optical Imaging Technologies

High‐temperature raman spectroscopy of SiO2 and GeO2 Polymorphs: Anharmonicity and thermodynamic properties at high‐temperatures

Philippe Gillet、Andrée Le Cléac'h、M. Madon1990-12-10Journal of Geophysical Research Atmospheres

The temperature dependence of the room pressure Raman spectra of the GeO 2 (hexagonal and tetragonal) and SiO 2 (quartz, coesite, and stishovite) polymorphs is presented. Several transformations upon heating are reported: α‐β quartz, coesite‐cristobalite, stishovite‐silica glass (with Si in four‐fold coordination). Fo…

High-pressure geophysics and materialsGlass properties and applicationsSolid-state spectroscopy and crystallography

Surface characteristics of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their PMMA blends

Hiroshi Inoue、Akihiro Matsumoto、Kimihiro Matsukawa 等 5 位作者1990-12-05Journal of Applied Polymer Science

Abstract Surface properties of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their poly(methyl methacrylate) (PMMA) blends have been intensively studied to draw a relationship between surface segregation behavior and adhesion performance. The fluoroalkylsilicone—PMMA block copolymers containing th…

Surface Modification and SuperhydrophobicityCopper Interconnects and ReliabilitySilicone and Siloxane Chemistry

Synthesis and characterization of some polyaniline–organic acceptor complexes

S. H. Khor、K. G. Neoh、E. T. Kang1990-12-05Journal of Applied Polymer Science

Abstract The charge transfer (CT) interactions between polyemeraldine (PEM) and six organic electron acceptors were studied. The complexing ability of the acceptors, based on the maximum attainable electrical conductivity of the resulting complex, could be arranged in the following ascending order:tetrachloro‐ p ‐benz…

Organic Electronics and PhotovoltaicsConducting polymers and applicationsAnalytical Chemistry and Sensors

Preparation of ultra‐high modulus polyvinyl alcohol fibers by the zone‐drawing method

Toshio Kunugi、Tamio Kawasumi、Takashi Ito1990-12-05Journal of Applied Polymer Science

Abstract The zone‐drawing method has been applied to prepare ultra‐high modulus polyvinyl alcohol fibers. First, the suitable temperature for zone‐drawing was decided. In the first zone drawing, when drawing temperature was as high as near melting point, the highest draw ratio and modulus were obtained. The modulus wa…

Polymer crystallization and propertiesHigh voltage insulation and dielectric phenomenaFiber-reinforced polymer composites

Solvent effect on thermal degradation of polystyrene

Shimio Sato、Tadahiro Murakata、Syunji Baba 等 5 位作者1990-12-05Journal of Applied Polymer Science

Abstract The thermal degradation of polystyrene (PS) in various kinds of solvents was studied in the temperature range from 300 to 450°C. The conversion of PS to low molecular weight products was dependent on the hydrogen donating ability of the solvents used: Solvents with greater donating ability resulted in less co…

Polymer crystallization and propertiesMicroplastics and Plastic PollutionPolymer Science and PVC

Nitrogen plasma treatment of polyethylene and polystyrene in a remote plasma reactor

Renate Foerch、N. S. McIntyre、R. N. S. Sodhi 等 4 位作者1990-12-05Journal of Applied Polymer Science

Abstract The effect of a remote nitrogen plasma on polyethylene and polystyrene was studied. The gas flow rate, the dilution of reactant gas, exposure times, and reactor base pressure were all found to have a large impact on the efficiency of nitrogen incorporation. Optimum conditions caused 18 atom % nitrogen to be i…

Surface Modification and SuperhydrophobicityRecycling and Waste Management TechniquesElectron and X-Ray Spectroscopy Techniques

Barrier layers for realization of high capacitance density in SrTiO3 thin-film capacitor on silicon

Toshiyuki Sakuma、Shintaro Yamamichi、S. Matsubara 等 5 位作者1990-12-03Applied Physics Letters

High dielectric constant SrTiO3 thin films were sputter deposited on barrier layers/Si substrate to fabricate a capacitor for dynamic random access memories. Dielectric constant (εr) values of 140–210 were achieved for the 150-nm-thick SrTiO3 films using a Pt/Ti or Pt/Ta double-layer barrier. In the Pt(50 nm)/Ti(10 nm…

Ferroelectric and Piezoelectric MaterialsSemiconductor materials and devicesAcoustic Wave Resonator Technologies

Diffusion coefficient increases with density in hard ellipsoid liquid crystals

Michael P. Allen1990-12-03Physical Review Letters

Molecular-dynamics simulations of highly nonspherical rodlike and platelike molecules reveal that one of the two diffusion coefficients in the nematic-liquid-crystal phase increases with density, reaches a maximum, and decreases, while the other coefficient decreases monotonically in the usual way. This effect seems t…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesSurfactants and Colloidal Systems

Reverse Monte Carlo simulation for the analysis of EXAFS data

S. J. Gurman、R L McGreevy1990-12-03Journal of Physics Condensed Matter

The authors describe the application of the reverse Monte Carlo simulation technique to the analysis of EXAFS data. This technique generates a series of three dimensional particle configurations which are consistent with the experimental EXAFS spectrum. No input information other than the density and the chemical comp…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsTransition Metal Oxide Nanomaterials

Brillouin scattering study of the anisotropic acoustic anomaly in ferroelectric and ferroelastic phase transitions

T. Yagi、Itaru Tatsuzaki、M. Tokunaga1990-12-01Ferroelectrics

A brief review is given for the Brillouin scattering studies of the dependence of the acoustic anomaly on the direction of sound propagation in structural phase transitions in ferroelectric and ferroelastic crystals. Near the ferroelectric phase transition temperature, the polarization fluctuation shows a characterist…

Acoustic Wave Resonator TechnologiesSolid-state spectroscopy and crystallographyOptical and Acousto-Optic Technologies

Reinvestigation of the Reaction of (NH4)2[Ce(N03)6] with Triphenylphosphine Oxide; the Crystal Structure and Magnetic Properties of mer-Ce(NO3)3(OPPh3)3 • 2 (CH3)2CO

Jianhua Lin、Evamarie Hey‐Hawkins、Hans Georg̀ von Schnering1990-12-01Zeitschrift für Naturforschung A

Abstract The reaction of (NH 4 ) 2 [Ce(NO 3 ) 6 ] with two equivalents of OPPh 3 (Ph = C 6 H 5 ) in acetonitrile yields Ce(NO 3 ) 4 (OPPh 3 ) 2 (1) in high yield, whereas using acetone as solvent affords mer- Ce(NO 3 ) 3 (OPPh 3 ) 3 • 2(CH 3 ) 2 CO (2), the yield of which is dependent on the reaction time. A crystal s…

Magnetism in coordination complexesLanthanide and Transition Metal ComplexesPolyoxometalates: Synthesis and Applications

Developments of Tritium Technology for Next-Step Fusion Devices under JAERI-DOE (LANL) Collaboration

Yuji Naruse、Kenji Okuno、Hiroshi Yoshida 等 6 位作者1990-12-01Journal of Nuclear Science and Technology

Since early 1980's, JAERI and DOE (LANL) have collaborated on developments of tritium technology for fusion reactors. About ten years collaboration, specially under the Annex III and IV agreements, has produced many remarkable outcomes on tritium fuel processing and tritium safety handling technologies. Under the Anne…

Fusion materials and technologiesNuclear reactor physics and engineeringRadioactive contamination and transfer

Order/disorder phase transitions of liquid-crystalline polymers with rigid groups in the side chains. A lattice theory

Finizia Auriemma、Paolo Corradini、Michele Vacatello1990-12-01The Journal of Chemical Physics

We present, in this paper, a lattice model of liquid-crystalline polymers with rigid groups attached to a semiflexible main chain through semiflexible spacers. The polymers are modeled as sequences of isodiametric units allocated at the nodes of the face-centered-cubic lattice. The model allows study of the phase beha…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesAdvanced Materials and Mechanics