Materials Literature
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High-quality T-shaped quantum wires are fabricated by cleaved-edge overgrowth with the molecular beam epitaxy on the interface improved by a growth-interrupt high-temperature anneal. Characterization by micro-photoluminescence (PL) and PL excitation (PLE) spectroscopy at 5 K reveals high uniformity, a sharp spectral w…
Amorphous silicon films doped with Y, La, Gd, Er, and Lu rare-earth elements (a-Si:RE) have been prepared by co-sputtering and studied by means of electron spin resonance (ESR), dc-magnetization, ion beam analysis, optical transmission, and Raman spectroscopy. For comparison the magnetic properties of laser-crystalliz…
Amorphous silicon-nitrogen thin films doped with rare-earth elements (a-SiN:RE; RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb, and Lu) have been prepared by co-sputtering and studied by means of electron spin resonance (ESR). It was found that the neutral dangling-bond density [D0] of a-SiN films decreases with the p…
The temperature-dependent polarization of SrTiO3 thin films is investigated using confocal scanning optical microscopy. A homogeneous out-of-plane and an inhomogeneous in-plane ferroelectric phase are identified from images of the linear electro-optic response. Both hysteretic and nonhysteretic behavior are observed u…
The phonon-mode decomposition of the electron-phonon coupling in the MgB2-like system Li_{1-x}BC is explored using first principles calculations. It is found that the high temperature superconductivity of such systems results from extremely strong coupling to only ~2% of the phonon modes. Novel characteristics of E_2g…
We present three-dimensional (3D) electron-positron momentum densities in Mg and Cd, reconstructed from 2D angular correlation of annihilation radiation data. By folding densities from the extended momentum space into the first Brillouin zone, we separated Fermi surfaces in various bands. Our results are in good agree…
Abstract The multiple melting behavior of poly(butylene succinate) (PBSu) was studied with differential scanning calorimetry (DSC). Three different PBSu resins, with molecular weights of 1.1 × 10 5 , 1.8 × 10 5 , and 2.5 × 10 5 , were cooled from the melt (150 °C) at various cooling rates (CRs) ranging from 0.2 to 50…
The high pressure behaviour of 3R-NbS2 has been investigated by angle-dispersive X-ray powder diffraction using diamond anvil cells up to 14 GPa. The compression behaviour of the structure is highly anisotropic. The compressibility perpendicular to the layers is 2.5 times higher than within the layers. A fit of a 3rd-…
We construct and apply an exchange-correlation functional for the one-dimensional Hubbard model. This functional has built into it the Luttinger-liquid and Mott-insulator correlations, present in the Hubbard model, in the same way in which the usual {\it ab initio} local-density approximation (LDA) has built into it t…
Four theoretical approaches to calculate momentum densities of electron-positron annihilation pairs (MDAP) in crystalline solids are confronted with 3D densities reconstructed from two-dimensional angular correlation (2D-ACAR) data for copper, chromium, and yttrium. It is shown that the Bloch-modified ladder theory, i…
Strain anisotropy can be well accounted for by the dislocation model of lattice distortion. In a texture-free powder or polycrystal, or if all possible Burgers vectors are equally populated, the dislocation contrast factors are a linear function of the fourth-order invariants of the hkl indices. Using this relation th…
Laser-induced cavitation bubbles near a curved rigid boundary are observed experimentally using high-speed photography. An image theory is applied to obtain information on global bubble motion while a boundary integral method is employed to gain a more detailed understanding of the behaviour of a liquid jet that threa…
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The structural properties of ${\mathrm{LaCoO}}_{3}$ were studied by means of high-resolution neutron powder diffraction in the temperature range $5<~T<~1000\mathrm{K}.$ Changes of the ${\mathrm{Co}}^{+3}$ spin states in this temperature interval are shown to affect not only the unit-cell volume, as previously kn…
Gold nanoshells have been synthesized by reacting aqueous HAuCl4 solutions with solid templates such as silver nanoparticles. The morphology, void space, and wall thickness of these hollow nanostructures were all determined by the templates, which were completely converted into soluble species during the replacement r…
The dielectric properties, internal friction, and Young’s modulus of (1−x%) Pb(Mg1/3Nb2/3)O3−x%PbTiO3 (for x=13, 23, and 33) ceramics have been measured. A phase-transition-like internal friction peak associated with Young’s modulus softening has been observed at temperature TR–F, which can be attributed to the relaxo…
The spherulitic growth mechanism of lysozyme crystals from aqueous solutions was examined quantitatively by taking advantage of a “buffer zone” of liquid–liquid phase separation occurring in lysozyme aqueous solution. This buffer zone technique allows us to obtain constant concentrations in both liquid phases during t…
The adopted crystal structure of the $\mathrm{AB}{\mathrm{O}}_{3}$ perovskites is determined by the balance between the interaction of the semicore states of the A and B atoms and oxygen ions. Topological considerations show that the structural setup always stabilizes the cubic phase at large pressures, while small or…
Epitaxial SrBi2Nb2O9 thin films have been grown by pulsed-laser deposition on (110)Pt bottom electrode epitaxially grown on (110) SrTiO3 by dc sputtering. X-ray φ-scans and electron channeling patterns reveal the epitaxial growth of the (116) SrBi2Nb2O9/(110)Pt bilayers. The hysteresis loop, dielectric response, and c…
First-principles total-energy calculations on hexagonal-close-packed (hcp) and body-centered-tetragonal (bct) states of bulk elemental magnesium have been made with a full-potential electronic structure program with both the local-density approximation and the generalized gradient approximation. The unique paths [call…