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Bulk and surface electronic structure of hexagonal boron nitride

Alessandra Catellani、M. Posternak、A. Baldereschi 等 4 位作者1987-10-15Physical review. B, Condensed matter

Accurate full-potential self-consistent linearized augmented-plane-wave (FLAPW) calculations have been carried out for hexagonal boron nitride. The resulting energy-band structure indicates that this material is an indirect-gap insulator and shows the existence of two unoccupied interlayer bands, similar to those foun…

Graphene research and applicationsBoron and Carbon Nanomaterials ResearchSurface and Thin Film Phenomena

A numerical investigation of nematic ordering based on a simple hard-rod model

Sin‐Doo Lee1987-10-15OpenAlex

On the basis of a simple functional scaling, we have constructed the direct generalization of the Carnahan–Starling equation for the free energy of a hard sphere fluid to a nematic liquid crystal. The orientational degrees of freedom are completely decoupled from translational ones under that scaling, which is equival…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesTheoretical and Computational Physics

Thermodynamic theory of PbTiO3

M. J. Haun、Eugene Furman、S. J. Jang 等 5 位作者1987-10-15OpenAlex

A phenomenological thermodynamic theory of PbTiO3 was developed using a modified Devonshire form of the elastic Gibbs free energy. The spontaneous strain as a function of temperature was determined from pure sol-gel derived PbTiO3 powder and used with selected data from the literature to determine the coefficients of…

Ferroelectric and Piezoelectric MaterialsAdvanced MEMS and NEMS TechnologiesAcoustic Wave Resonator Technologies

The pressure and temperature dependence of the dielectric properties of Pb(Co1/3Nb2/3)O3

Tadashi Hachiga、S Fujimoto、Naohiko Yasuda1987-10-14Journal of Physics D Applied Physics

The dielectric properties, such as the real in ' and imaginary in " parts of the complex permittivity and the spontaneous polarisation P s of single-crystal and ceramic Pb(Co 1/3 Nb 2/3 )O 3 with a diffuse phase transition (DPT), were measured under various pressures up to 6 kbar. The value of in ' shows a broad maxim…

Ferroelectric and Piezoelectric MaterialsSolid-state spectroscopy and crystallographyMicrowave Dielectric Ceramics Synthesis

Absolute total cross section measurements for intermediate energy electron scattering: III. Ne and Ar

A. Zecca、Stefano Oss、Grzegorz P. Karwasz 等 5 位作者1987-10-14Journal of Physics B Atomic and Molecular Physics

Absolute total cross section measurements are presented for e - -Ne and e - -Ar scattering. The covered energy range spans from 100 to 3000 eV. The overall systematic uncertainty was +or-2.4%, the random uncertainty was +or-1.5% and the angular resolution error was less than 0.5%. A comparison with existing experiment…

Atomic and Molecular PhysicsX-ray Spectroscopy and Fluorescence AnalysisElectron and X-Ray Spectroscopy Techniques

Cubic-lattice simulation of the dynamics of a collapsed polymer chain

J. Naghizadeh、J. M. Kovac1987-10-12Physical Review Letters

The end-to-end vector relaxation time, \ensuremath{\tau}, and center-of-mass diffusion constant, D, of a nonintersecting chain with nearest-neighbor attractive interactions were investigated. Data were obtained by Monte Carlo simulation of motion as a function of temperature in the free-draining approximation. The ran…

Material Dynamics and PropertiesTheoretical and Computational PhysicsRheology and Fluid Dynamics Studies

Hybrid aligned cholesteric: A novel liquid-crystal alignment

M. R. Lewis、M C K Wiltshire1987-10-12Applied Physics Letters

A hybrid aligned cholesteric (HAC) liquid-crystal (LC) structure is reported. The LC director tilt varies from a small angle at one surface to almost 90° at the other, while incorporating a helical twist. Cells having one surface treated with rubbed polyvinyl alcohol and the other with the organosilane octadecyltrieth…

Liquid Crystal Research AdvancementsSurfactants and Colloidal SystemsPlant Reproductive Biology

Structural alterations in the amorphous-to-crystalline transformation of lead pyrophosphate

B. C. Sales、J. O. Ramey、L. A. Boatner1987-10-12Physical Review Letters

The detailed structural changes that occur during the isothermal transition from a glass to a single-phase crystalline solid have been determined for the first time by use of the modern technique of high-performance liquid chromatography. Quantitative measurements of the evolution of the type and relative concentratio…

Glass properties and applicationsThermal and Kinetic AnalysisAdsorption, diffusion, and thermodynamic properties of materials

Circular dichroism spectra and electronic rotatory strengths of the samarium 4f→ 4ftransitions in Na3[Sm(oxydiacetate)3]·2NaClO4·6H2O

P. Stanley May、Michael F. Reid、F. S. Richardson1987-10-10Molecular Physics

Axial absorption and circular dichroism (CD) spectra are reported for single crystals of Na3[Sm(oxydiacetate)3]·2NaClO4·6H2O over the spectral region 17 600–30 500 cm-1. Within this region, 213 individual (4f → 4f) crystal-field transitions may occur from the ground crystal-field level of Sm3+. Each of these transitio…

Lanthanide and Transition Metal ComplexesSolid-state spectroscopy and crystallographyElectron Spin Resonance Studies

High-Temperature Cubic Boron Nitride P-N Junction Diode Made at High Pressure

Osamu Mishima、Junzo Tanaka、Shinobu Yamaoka 等 4 位作者1987-10-09Science

A p-n junction diode of cubic boron nitride was made by growing an n-type crystal epitaxially on a p-type seed crystal at a pressure of 55 kilobars and a temperature of about 1700 degrees C. A temperature-difference solvent method was used for the crystal growth, and beryllium and silicon were doped as acceptors and d…

Semiconductor materials and devicesDiamond and Carbon-based Materials ResearchBoron and Carbon Nanomaterials Research

Electron paramagnetic resonance, optical and magnetic studies of Tb3+ in lanthanide nicotinate dihydrates

J M Baker、Clyde A. Hutchison、M. J. M. Leask 等 6 位作者1987-10-08Proceedings of the Royal Society of London A Mathematical and Physical Sciences

Abstract Optical absorption and fluorescence, magnetic susceptibility and electron magnetic resonance experiments have been made of Tb3+, 4f8, ions in lanthanide nicotinate dihydrate single crystals. Optical absorption spectroscopy in undiluted terbium nicotinate dihydrate (TbND) indicates that the ground state of Tb3…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsSolid-state spectroscopy and crystallography

The stability of superspheres

Jeremy J. Ramsden1987-10-08Proceedings of the Royal Society of London A Mathematical and Physical Sciences

Abstract The stability of superspheres containing a few tens of particles, formed by the aggregation of weakly charged spherical colloidal crystalites, can be explained by the existence of two opposing forces of different range within the superspheres: long-range electrostatic repulsion and shortrange attractive dispe…

Material Dynamics and PropertiesTheoretical and Computational PhysicsPickering emulsions and particle stabilization

A new set of composition variables for the representation of reactive-phase diagrams

Domingos Barbosa、Michael F. Doherty1987-10-08Proceedings of the Royal Society of London A Mathematical and Physical Sciences

Abstract A set of transformed composition variables is introduced for the representation of reactive-phase diagrams. These variables are superior to mole fractions because in the new representation, the non-reactive limits are well defined, the equilibrium surfaces are tangent at azeotropic states, and the number of l…

Crystallization and Solubility StudiesThermal and Kinetic AnalysisChemical Thermodynamics and Molecular Structure

Neutron diffraction study of zoisite at 15 Κ and X-ray study at room temperature

J. V. Smith、J. J. Pluth、James W. Richardson 等 4 位作者1987-10-01Zeitschrift für Kristallographie - Crystalline Materials

Article Neutron diffraction study of zoisite at 15 Κ and X-ray study at room temperature was published on October 1, 1987 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 179, issue 1-4).

Crystal Structures and PropertiesX-ray Diffraction in CrystallographyInorganic Fluorides and Related Compounds

Ruthenium(III)triphosphide RuP3: Preparation, crystal structure and properties

Wolfgang Hönle、Reinhard K. Kremer、Hans Georg̀ von Schnering1987-10-01Zeitschrift für Kristallographie - Crystalline Materials

Article Ruthenium(III)triphosphide RuP3: Preparation, crystal structure and properties was published on October 1, 1987 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 179, issue 1-4).

Metallurgical and Alloy Processes

Charging behavior of polyethylene and ionomers

M. G. Broadhurst、A.S. DeReggi、G. T. Davis 等 4 位作者1987-10-01OpenAlex

Space charge may lower the breakdown strength of solid insulation by making local electric fields bigger than the applied field. One extensive study[1] of this phenomenon led to a proposal to blend crosslinked polyethylene (XLPE) insulation with an ionomer to reduce space charge build-up. The authors used contact elec…

Advanced Sensor and Energy Harvesting MaterialsHigh voltage insulation and dielectric phenomenaPower Line Communications and Noise

DC cable insulation conductivity as a function of temperature, polarity changes and time

M. Henriksen、E. Larsen、Hanna Johannesson1987-10-01OpenAlex

A detailed description of our revised method of preparing PE and XLPE samples to be used for the investigation of the fundamental parameters of these two materials will be presented. The latest findings regarding the long term conductivity of the specimens under high and constant electrical field, when temperature was…

High voltage insulation and dielectric phenomenaElectrical Fault Detection and ProtectionThermal Analysis in Power Transmission

XRD studies of portlandite present in hydrated Portland cement paste

Alfred Zürz、I. Odler1987-10-01Advances in Cement Research

Synopsis The effect of hydration time, water/solids ratio and addition of melamine sulphonate or naphthalene sulphonate resins on the I (001) /I (101) XRD peak intensity ratio of portlandite formed in the hydration of pure tricalcium silicate or Portland cement was studied. It was found that this ratio does not remain…

Concrete and Cement Materials ResearchThermal and Kinetic AnalysisX-ray Diffraction in Crystallography

Physics Testing at Fort St. Vrain — A Review

J. R. Brown、Rick Hackney、V. Malakhof 等 4 位作者1987-10-01Nuclear Science and Engineering

Fort St. Vrain (FSV) is the only graphite-moderated, helium-cooled nuclear power plant in the United States. It was preceded by the 40-MW(electric) Peach Bottom high-temperature gas-cooled reactor (HTGR), which was permanently shut down in 1975. The Public Service Company of Colorado owns and operates FSV, and the cor…

Nuclear reactor physics and engineeringGraphite, nuclear technology, radiation studiesNuclear and radioactivity studies

Measurement of space charge fields in polymers

A.S. De Reggi、M. G. Broadhurst、G. T. Davis 等 4 位作者1987-10-01OpenAlex

This paper reports progress in measuring electric fields due to space charge in continuous dielectric media by-means of the thermal pulse method[1–3]. This work is pertinent to the study of charge injection and transport processes as well as to the study of the effects of space charge on the dielectric breakdown of el…

Advanced Fiber Optic SensorsHigh voltage insulation and dielectric phenomenaThermography and Photoacoustic Techniques