Materials Literature
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Persistent photoconductivity has been observed in a perovskite manganite doped with an alkali metal element, ${\mathrm{Pr}}_{0.75}{\mathrm{Na}}_{0.25}{\mathrm{MnO}}_{3}.$ Considering the shallow penetration depth $(\ensuremath{\sim}0.1\ensuremath{\mu}\mathrm{m})$ of visible light, the increase of the conductance is es…
Thermal conductance G, thermal capacitance H, and the time constant τ are major parameters to be determined in the design of bolometer devices and, therefore, it is an important task to evaluate these thermal parameters experimentally for design verification. In this work, a technique has been developed to determine t…
A simple and general technique for producing a suspended nanofiber has been developed using coordinate markers and a sacrificial layer of poly(methylmethacrylate). The simple procedure does not involve etching processes or chemical vapor deposition and makes it easier to investigate the physical properties of nanofibe…
In this letter, we present the results of the fabrication and characterization of 5 mol % MgO doped Ba0.7Sr0.3TiO3 (BST) films grown on Pt/TiN/SiO2 coated on Al2O3 substrates using the rf magnetron sputtering technique. The dielectric and electrical properties of Ba0.7Sr0.3TiO3 thin film were found to improve obviousl…
Abstract The initiation of the electrochemical growth of polythiophene thin films was studied by X‐ray photoelectron spectroscopy (XPS), electron probe micro analysis (EPMA), and mainly by scanning electron microscopy (SEM). The films were deposited on SnO 2 ‐coated glass in a classical three‐electrode cell. Depositio…
Electrical ac conductivity measurements on alkali triborate glasses ( M2O x 3B2O3, M = Li, Na, K, and Rb) were performed at temperatures down to 8 K and frequencies up to 1 GHz. All samples show a nearly constant dielectric loss (NCL), at the limit of high frequencies and/or low temperatures. The magnitude of the NCL…
Copper nitride films were grown by molecular-beam epitaxy of copper in the presence of nitrogen from a radio-frequency atomic source on (001) γ′-Fe4N/(001)MgO or directly on MgO substrates. The structural properties of the Cu3N films were found to be very dependent on the substrate and on the deposition temperature. A…
A method is developed to simultaneously measure the Seebeck coefficient and thermal conductivity in the cross-plane direction of thin films and applied to an n-type Si/Ge quantum-dot superlattice. In this method, an Au/Cr pattern serves as both a heater and a thermometer, and a microprobe is prepared between the heate…
We studied the polarization dependence of the resonance Raman spectra for several different isolated single-wall carbon nanotubes (SWNTs). One isolated SWNT acts as a dipolar antenna, polarized along the tube axis. For light polarized parallel to the tube axis, the strong resonance-effect breaks the symmetry-selection…
The optical and electrical properties of Mn-doped epitaxial GaN were studied. Low-temperature optical absorption measurements indicate the presence of a Mn-related band with a well-resolved fine structure. The zero-phonon line is at 1.418±0.002 eV with a full width at half maximum of 20±1 meV. Two pseudolocal vibratio…
We formulate a Hartree-Fock-LAPW method for electronic band structure calculations. The method is based on the Hartree-Fock-Roothaan approach for solids with extended electron states and closed core shells where the basis functions of itinerant electrons are linear augmented plane waves. All interactions within the re…
Non-ionized media subject to strong fields can become locally ionized by penetration of finger-shaped streamers. We study negative streamers between planar electrodes in a simple deterministic continuum approximation. We observe that for sufficiently large fields, the streamer tip can split. This happens close to Firs…
We have investigated several ultra-thin copper nanobridges between supporting layers using a classical molecular dynamics simulation and a many-body potential function of the second-moment approximation of tight-binding scheme. This investigation has shown a part of the thermal properties of nanobridges, the tension i…
Wurtzite GaN:Mn films on sapphire substrates were successfully grown by use of the molecular beam epitaxy (MBE) system. The film has an extremely high Curie temperature of around 940 K, although the Mn concentration is only about 3 ~ 5 %. Magnetization measurements were carried out in magnetic fields parallel to the f…
The superconducting and structural properties of a series of Mg1-xAlxB2 samples have been investigated. X-ray diffraction results confirmed the existence of a structural transition associated with the significant change in inter-boron layer distance as reported previously by Slusky et al. Moreover,transmission-electro…
In this letter, we investigate the upconversion properties of 19ZnO–80TeO2–1Er2O3 glass after excitation into the I11/24 level using 980 nm radiation. At an excitation power density of 880 W/cm2, green emission [(2H11/2, 4S3/2)→4I15/2] dominates the upconversion spectrum with an efficiency of 0.16%. Temporal studies r…
Atomistic simulations using a combination of classical force field and density-functional theory (DFT) show that carbon atoms remain essentially sp(2) coordinated in either bent tubes or tubes pushed by an atomically sharp atomic-force microscope (AFM) tip. Subsequent Green's-function-based transport calculations reve…
Light scattering by individual Ag nanoparticles and structures have been studied spectroscopically. Individual particles were selected and manipulated with a micromanipulator installed inside a scanning electron microscope (SEM). With typical particle dimensions of some 100 nm, the plasma resonances of particles and t…
The cross-plane thermal conductivity of four Si/Si0.7Ge0.3 superlattices and three Si0.84Ge0.16/Si0.76Ge0.24 superlattices, with periods ranging from 45 to 300 and from 100 to 200 Å, respectively, were measured over a temperature range of 50 to 320 K. For the Si/Si0.7Ge0.3 superlattices, the thermal conductivity was f…
The observation of strong magnetoelectric effects is reported in layered composites of ferromagnetic lanthanum manganites and piezoelectric lead zirconate titanate (PZT). Studies were made on thick-film structures of ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ (LSMO)-PZT and ${\mathrm{La}}_{0.7}{\mathrm…