Materials Literature
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We identify a fundamental morphological instability of mobile dislocations in crystals and related line defects. A positive gradient in the local driving force along the direction of defect motion destabilizes long-wavelength vibrational modes, producing a ``fingering'' pattern. The minimum unstable wavelength scales…
Relaxations at nonpolar surfaces of III-V compounds result from a competition between dehybridization and charge transfer. First principles calculations for the (110) and (10$\bar{1}$0) faces of zincblende and wurtzite AlN, GaN and InN reveal an anomalous behavior as compared with ordinary III-V semiconductors. Additi…
Fullerides are crystals made from C60 molecules. When doped with alkali metals the valence electrons of the alkali atoms are transfered to the C60 molecules. We show how to set up a model Hamiltonian to describe the correlated hopping of these electrons between C60 molecules. Then we discuss Monte Carlo methods for su…
Introduction Collision experiments provide a considerable portion of our information on the interactions between particles, as well as on the internal structure of the particles themselves, in all of the subfields of modern physics. When the interactions between particles are large, information is obtained primarily o…
Graphoepitaxial Ni50Ti50 films were grown on Si substrates by sputter deposition of an alloy target. The microstructure evolution of the film was investigated by hot stage atomic force microscopy. The topological features of the martensitic graphoepitaxial Ni50Ti50 films are directly associated with etch pits on the s…
Local thermal conductivity inside grains of high-quality polycrystalline diamond grown by chemical vapor deposition is measured at room temperature with micrometer spatial resolution. An effective conductivity is determined by choosing experimental conditions where the measured heat flow extends over adjacent grains.…
We have studied nucleation and growth of diamond on nickel substrate by microwave plasma assisted chemical vapor deposition followed by in situ carbon–hydrogen solution treatment. The Raman depth profiles of isolated diamond crystals on the (100) and (111) surfaces were measured by confocal Raman spectroscopy. In the…
We show that the electrical properties of nitrogen-doped nominally undoped polycrystalline chemical vapor deposited diamond films are modified by post-deposition heating in an oxidizing atmosphere. We found that the first heating cycle in air in the temperature range of 300–673 K decreased the graphitization content s…
Single-pulse laser ablation of polyimide was investigated by using focused UV-Ar+-laser radiation (λ≈302 nm, 140 ns⩽τl⩽50 ms) and atomic force microscopy. The results clearly demonstrate that the ablation rates do not depend on the total dose only, but depend as well on the duration of the laser pulses, τl. The experi…
A pure carbon quantum dot can be designed by introducing pentagon-heptagon defects in a carbon nanotube. This system has completely confined electronic states induced by the presence of topological defects. By varying the distance between the pentagon-heptagon pairs, the energy difference, spatial confinement, and num…
Using mean-field theory with P 2 θ 2 coupling term in the free energy expansion, we calculate the polarization as a function of concentration for the AC * phase transition in a binary mixture of C7 and 10.O.4 liquid crystalline material. Our calculated values of polarization are in good agreement with the experimental…
Pulsed laser excitation induced conductance changes in colossal magnetoresistance material ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ were studied on the picosecond time scale. A two-component signal was seen consisting of a fast positive transient associated with the paramagnetic insulating state and…
Structural properties of the (NaCl-type) and (CsCl-type) phases of alkaline-earth oxides and their phase transition have been investigated with the periodic ab initio linear combination of atomic orbitals method implemented in the CRYSTAL program. The geometries have been optimized and the bulk modulus evaluated. The…
In colloidal suspensions containing a binary mixture of hard spheres depletion forces occur which substantially contribute to the interaction of the larger spheres among themselves and a wall, respectively. We investigated the depletion force acting on a large colloidal polystyrene sphere immersed in a solution of sma…
We present a simple ionic model which successfully reproduces the various types of compositional long-range order observed in a large class of complex insulating perovskite alloys. The model assumes that the driving mechanism responsible for the ordering is simply the electrostatic interaction between the different io…
We discuss magnetotransport in a low density electron gas coupled to spin fluctuations near and above a ferromagnetic transition. Provided the density is low enough [ $n\ensuremath{\lesssim}1/{\ensuremath{\xi}}^{3}(T)$, with $\ensuremath{\xi}(T)$ the ferromagnetic correlation length], spin polarons form in an intermed…
Direct evidence for freezing in two relaxor ferroelectrics, PbMg1/3Nb2/3O3 and PbSc1/2Ta1/2O3, at a certain temperature Tf≠0 K was obtained from the temperature dependence of the maximum relaxation time, τmax. It was shown that τmax(T) follows the Vögel–Fulcher (VF) law, and tends toward infinity as temperature approa…
To synthesize effective compatibilizers for the compatibilization of acrylic polymer–silk fibroin blend fibers, the homogeneous graft copolymerization of acrylonitrile onto silk fibroin, initiated by potassium persulfate–sodium bisulfite redox system in 60 wt % ZnCl2 aqueous solution was investigated. The percentage g…
Results of differential scanning calometry (DSC), x-ray diffraction (XRD), and F19 nuclear magnetic resonance (NMR) of InF3-based glasses, treated at different temperatures, ranging from glass transition temperature (Tg) to crystallization temperature (Tc), are reported. The main features of the experimental results a…
We present the results of a spectroscopic study carried out on a solid sample of 5,5″-bis(dicyanomethylene)-5,5″-dihydro-Δ2,2′:5′,2″-terthiophene. This compound bears a heteroquinonoid structure in its ground state and could be considered as a model of the structural changes induced by the different types of charge ca…