Materials Literature
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Zn 1 − x Cd x O thin films were deposited on (0001) sapphire substrates by pulsed-laser deposition. Structural and optical properties of Zn1−xCdxO films were strongly correlated to the processing conditions. The composition of the films varied nonmonotonically as a function of deposition temperatures due to the differ…
The phenomenon of contact angle hysteresis was studied on smooth films of polyimide, a polymer type used in the microelectronic industry, by dynamic cycling contact angle measurements based on axisymmetric drop shape analysis-profile in combination with variable angle spectroscopic ellipsometry (VASE). It was found th…
Wet-chemistry techniques, involving the previous elaboration of reactive citrate precursors, have been used to prepare Sr2FeMoO6 double perovskite in polycrystalline form. This material has been characterized by x-ray and neutron powder diffraction, magnetic, and magnetotransport measurements. It exhibits a ferromagne…
Protonated Schiff bases (PSBs) of polyenals constitute a class of light-driven switchers selected by biological evolution that provide model compounds for the development of artificial light-driven molecular devices or motors. In the present paper, our primary target is to show, through combined computational and expe…
Colloidal submicrometer-diameter amorphous silicon (a-Si) particles are synthesized with >90% yield by thermal decomposition of trisilane (Si3H8) in supercritical hexane at temperatures ranging from 400 to 500 degrees C and pressures up to 345 bar. A range of synthetic conditions was explored to optimize the quality o…
We have studied the slow linear viscoelastic response of wet aqueous foams by macroscopic creep compliance measurements, combined to a diffusing-wave spectroscopy investigation of the local dynamics. The data strongly suggest that this rheological response arises from two distinct relaxation mechanisms: The first is d…
The anisotropic magnetic properties of a series of epitaxial Ga1−xMnxAs films with thicknesses ranging from 0.2to6.8μm were investigated using magnetometry and x-ray diffraction. The films all show a distinct uniaxial contribution to the magnetic anisotropy along the in-plane [110] direction, whose relative importance…
The electronic structure of copper-phthalocyanine (CuPc) has been studied both experimentally and theoretically. Experiments have been performed on alpha and beta crystalline phases, using photoemission spectroscopy to probe core levels and valence band spectra. Different photon energies have been used, in order to pr…
We measured zirconium tungstate's elastic constants ${C}_{ij}$. This compound shows relatively soft, nearly isotropic elastic constants with normal Poisson ratios and no approach to Born instability. ${\mathrm{Z}\mathrm{r}\mathrm{W}}_{2}{\mathrm{O}}_{8}$ shows normal ambient-temperature elastic constants ${C}_{ij}$, b…
Low-temperature photoluminescence (PL) studies of individual semiconducting single-walled carbon nanotubes reveal ultranarrow peaks (down to 0.25 meV linewidths) that exhibit blinking and spectral wandering. Multiple peaks appear within bands previously assigned to nanotubes of certain chiralities, indicating the exis…
We have examined the thermal stability of TiO2-terminated SrTiO3(100) surfaces obtained by buffered HF etching and widely used as substrates for oxide film growth. In situ coaxial impact-collision ion scattering spectroscopy was used to measure the composition of the terminating atomic layer at temperatures up to 1000…
A statistical mechanical theory of collective dynamic barriers, slow segmental relaxation, and the glass transition of polymer melts is developed by combining, and in some aspects extending, methods of mode coupling, density functional, and activated hopping transport theories. A coarse-grained description of polymer…
We examine the storage and release of internal stresses in shape memory polymers reinforced with a dispersion of nanometer-scale SiC particles. A quantitative Rietveld analysis of diffraction peaks was used to measure changes in the lattice parameter of the SiC particles after permanent deformation at 25°C, and subseq…
Thin films of ordered double-perovskite Sr2CrReO6 have been grown epitaxially onto SrTiO3 substrates by sputtering, and their microstructural, electrical, and magnetic properties are investigated. It is found that a wide growth-temperature range of at least 700–800°C can yield epitaxial films with superior magnetic pr…
The main goal of electronic structure methods is to solve the Schroedinger equation for the electrons in a molecule or solid, to evaluate the resulting total energies, forces, response functions and other quantities of interest. In this paper we describe the basic ideas behind the main electronic structure methods suc…
Heat-capacity behavior in the presence of externally applied magnetic field (H) up to 140 kOe is investigated (2-35 K) for the quasi-1-dimensional compound, Ca3Co2O6, believed to order magnetically with the so-called partially disordered anti-ferromagnetic structure. The results reveal that there is a shift of the mag…
We demonstrate the physical principles for the construction of a nanometer sized magnetoresistance device based on the Aharonov-Bohm effect. The proposed device is made of a short single-walled carbon nanotube (SWCNT) placed on a substrate and coupled to a tip. We consider conductance due to motion of electrons along…
In a diluted magnetic semiconductor system, the exchange interaction between magnetic impurities has two independent components: a direct antiferromagnetic interaction and a ferromagnetic interaction mediated by charge carriers. Depending on the system parameters, the ground state of the system may be ordered either f…
Finite element methods are used to study non-adhesive, frictionless contact between elastic solids with self-affine surfaces. We find that the total contact area rises linearly with load at small loads. The mean pressure in the contact regions is independent of load and proportional to the rms slope of the surface. Th…
We propose a new physically-based ``multifractal stress activation'' model of earthquake interaction and triggering based on two simple ingredients: (i) a seismic rupture results from activated processes giving an exponential dependence on the local stress; (ii) the stress relaxation has a long memory. The combination…