Materials Literature
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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…
Nuclear magnetic resonance of Si29 is used to study structural properties of porous silicon and siloxene. Evidence for changes in the chemical shift of porous silicon due to quantum confinement could not be observed. A hydride phase exhibiting a chemical shift of −75 ppm versus tetramethyl silane (TMS) is found in bot…
Electron spin resonance (ESR) spectra at X-band microwave frequencies are reported for dopant ions in (CGGO), (SGGO), (LGGO) and (LGS). The ESR measurements identify two distinct sites for in CGGO and SGGO and a single site in LGGO and LGS characterized by spin S = 3/2 for ions in the ground state. In CGGO a sharp lin…
Mixed sesquioxides (x = 0.10, 0.20, 0.60, 1.00, 1.60 and 1.80) in the cubic (C) phase were obtained by precipitation and subsequent sintering. Cubic and were transformed into monoclinic (B) phases at 1400 K and 1600 K respectively. The transformation is reconstructive in character. All of the structures were refined u…
The ground-state electronic structures of ferromagnetic and antiferromagnetic perovskite in the ideal cubic phase have been investigated using the ab initio periodic Hartree - Fock approach. The system is a wide-gap insulator. The antiferromagnetic phase is correctly predicted to be the more stable (0.07 eV per Mn ato…
Zuwachs bei den Komplexen zweiwertiger 4f‐Elemente Waren bisher Eu II ‐Yb II ‐ und Sm II ‐Komplexe bekannt, so wurde nun erstmals auch ein Tm II ‐Komplex zugänglich. Die intensiv grüne Titelverbindung wurde durch Reaktion von TmI 3 mit Tm in Dimethoxyethan hergestellt. Der lichtempfindliche Komplex hat eine pentagonal…