Materials Literature
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Raman-scattering measurements have been carried out for crystals of the ${\mathrm{RTiO}}_{3}$ (R=La,Ce,Pr,Nd,Sm,Gd) system whose members are Mott-Hubbard insulators. ${\mathrm{RTiO}}_{3}$ has an orthorhombically distorted perovskite unit cell. The distortion increases systematically from ${\mathrm{LaTiO}}_{3}$ to ${\m…
Results of surface photovoltage spectroscopy on free-standing porous silicon films fabricated from boron-doped Si wafers of various resistivities are presented. We find that all the films have bandtails, which are about 0.3 eV wide, and their optical band gap is about 2 eV. The majority carriers in the strongly lumine…
Segregation at GaAs/AlAs (001) heterointerfaces has been studied experimentally by an in situ electron diffraction technique during molecular-beam epitaxy and by ex situ transmission electron microscopy. Whereas the GaAs-on-AlAs interface is abrupt, we find Ga segregating up to 20 crystal planes when depositing AlAs o…
Sequential anionic polymerization of styrene and divinylbenzene (DVB) is known to lead to the formation of star-shaped polymers. This ‘arms-first’ method has been widely used and studied. It is known that this polymerization forms stars with anionically active cores. This article is concerned with the attempt to make…
The adsorption of Cs on a ${\mathrm{TiO}}_{2}$(110) rutile surface was investigated at 130--800tK using x-ray photoelectron spectroscopy, x-ray excited Auger electron spectroscopy, temperature-programmed desorption, work-function, and band-bending measurements. Below room temperature, the Cs displays a Stranski-Krasta…
The expansion dynamics of the plasma produced by excimer laser ablation of BaTiO3 has been studied by spatially resolved optical emission spectroscopy over a broad gas pressure range (10−7–40 mbar), the gas being either reactive (oxygen) or inert (argon). The results obtained in both environments are qualitatively sim…
First-principles theory is shown to account for the unique low-temperature crystal structure of plutonium metal (\ensuremath{\alpha}-Pu). Also the observed, and debated, upturn of the equilibrium volume between neptunium and plutonium is reproduced and found to be a consequence of the different crystal structures for…
A brief review is given of applications of Monte Carlo simulations to study the dynamical properties of coarse-grained models of polymer melts, emphasizing the crossover from the Rouse model toward reptation, and the glass transition. The extent to which Monte Carlo algorithms can mimic the actual chain dynamics is cr…
We have investigated the influence of biaxial compressive strain on the thermodynamic properties of hydrogen in thin, single-crystal vanadium layers (0.9, 1.6, and 2.0 nm). At H/V0.1 (atomic ratio), the host-mediated H-H interaction was found to be attractive. For H/V>0.1, the interaction was found to be extremely…
The ideal magnetic Ericsson refrigeration cycle should have a constant induced magnetic entropy change as a function of temperature over the whole refrigeration range. To realize this condition using composite materials, a numerical method has been developed to determine the optimum proportions of the component materi…
Dielectric and physicochemical properties of a composite material prepared by incorporating carbon black particles into a polymer matrix were investigated. Two types of carbon blacks, having very different structures of aggregates, were used. The volume fraction of the carbon blacks ranged from 0.2% to 7%, i.e. below…
\ensuremath{\alpha}-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$,${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$, and FeO compounds are characterized by means of x-ray-absorption near-edge-structure spectroscopy at the oxygen K edge. Using increasing cluster sizes around the excited atom in the full multiple-scattering simulations, we…
We have investigated electrical and optical properties of the high-conductivity layers formed in both undoped and B-doped diamond films prepared by chemical vapor deposition. It is found that both hydrogenated undoped and B-doped diamond films have high-concentration holes of ∼1018 cm−3 at 297 K. These films exhibit l…
Several high temperature polyimides, as model polymers with various chain rigidities and chain orders, were synthesized through the polycondensation of p-phenylene diamine (PDA) with five different aromatic dianhydrides [i.e., pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 4,4′-oxydiphtha…
Lead zirconate titanate (PZT) films 60 μm in thickness have been fabricated using a new sol gel based process. PZT powders are dispersed in a sol gel matrix to form a 0–3 ceramic/ceramic composite. The dielectric properties of these films have been studied as a function of powder concentration, frequency, and temperat…
The relaxation behavior of poly(ethylene oxide) (PEO), intercalated in montmorillonite, a naturally occurring mica-type silicate, was studied by differential scanning calorimetry (DSC) and thermally stimulated dielectric depolarization (or thermally stimulated current, TSC). The materials were synthesized by melt or s…
The x-ray scattering from relaxed heteroepitaxial layers with the misfit dislocations randomly distributed at the interface between the layer and the substrate is analyzed theoretically and experimentally. The profiles of the x-ray-diffraction peaks and the reciprocal space maps of the intensity are measured and simul…
The orientation distribution of a textured polycrystalline material has been traditionally determined from a few individual pole figures of lattice planes hkl, measured by x-ray or neutron diffraction. A new method is demonstrated that uses the whole diffraction spectrum, rather than extracted peak intensities, by com…
Second harmonic generation in gallium-lanthanum-sulphide (Ga:La:S) and germanium sulphide + Ga:La:S glasses is investigated. It is shown that microcrystals of Ga:La:S and α phase of gallium-sulphide (α-Ga2S3), whose presence in the glass matrix is revealed by energy dispersive spectroscopy and x-ray diffraction analys…
We report on the observation of spin echo signals at the generalized Rabi frequency of a strongly driven two level system. The results are obtained for a radio-frequency transition of the nitrogen-vacancy center in diamond. A physical picture of the experiment is given in terms of the dressed-state basis, and the echo…