Materials Literature
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Abstract The influence of a nonpigmenting β‐nucleating additive in the crystallization of isotactic polypropylene (iPP) is investigated by differential scanning calorimetry and X‐ray diffraction. It is found that this additive induces the formation of a very high level of the trigonal modification of iPP. The crystall…
In this paper we simulate the resistive heating of carbon nanotubes (CNT's) during field emission (FE) using the one-dimensional heat equation including radiation and conductive losses. The simulations are in relatively good agreement with our recent experiments in which we measured the heating of individual CNT's to…
Brittle fracture in silicon is simulated with molecular dynamics utilizing a modified embedded atom method potential. The simulations produce propagating crack speeds that are in agreement with previous experimental results over a large range of fracture energy. The dynamic fracture toughness is found to be equal to t…
Applying the novel exact-exchange (EXX) Kohn-Sham method within time-dependent density-functional theory, we obtained the optical absorption spectrum of bulk silicon in good agreement with experiments including excitonic features. Analysis of the EXX kernel shows that inclusion of the Coulomb coupling of electron-hole…
A new achiral banana-shaped mesogen is presented which exhibits a nematic phase and an isotropic mesomorphic phase with spontaneous chiral ordering.
The study of quantum phase transitions, which are zero-temperature phase transitions between distinct states of matter, is of current interest in research since it allows for a description of low-temperature properties based on universal relations. Here we show that the crystal green dioptase Cu_6Si_6O_18 . 6H_2O, kno…
Experimental data obtained for PbFe$_{1 / 2}$Ta$_{1 / 2}$O$_{3}$ (PFT) and NaNbO$_{3}$: Gd (NaNbGd) single crystals show a diffused dielectric permittivity peak that is inherent to relaxor ferroelectrics. However some deviations from the normal relaxor properties were also observed and are under discussion. One of the…
We determine the effective dipolar interaction between single domain two-dimensional ferromagnetic particles (islands or dots), taking into account their finite size. The first correction term decays as 1/D^5, where D is the distance between particles. If the particles are arranged in a regular two-dimensional array a…
The mass transfer of interstitial impurities in a crystalline lattice under the influence of the fast-moving deformation disturbance of the type of a shock wave is considered. The velocity of the movement of the disturbance is supposed to be compared with the characteristic velocity of the relaxation of the diffusion…
In this paper we present a study of magnetic order of quantum Heisenberg spins on pyrochlore type lattices: a lattice of corner sharing tetrahedra. We use the Cluster Variation Approximation with the tetrahedron as basic cluster. We find that in case of anti-ferromagnetic nearest--neighbour exchange there is no long--…
For a single crystal of TmGa3, two-dimensional angular correlation of positron annihilation radiation spectra were measured and subjected to a deconvolution algorithm based on the Van Citter iterative method. The three-dimensional electron-positron momentum density was reconstructed both via the Cormack and a modified…
Electron-positron momentum densities in Y, reconstructed from two-dimensional angular correlation of annihilation radiation spectra, are compared with the theoretical predictions of fully-relativistic augmented plane-wave calculations. Knowledge of the theoretical densities and of the effects on them of certain symmet…
A reconstruction technique based on Radon transforms is used to obtain 3D electron momentum density rho(p) using nine recently measured high-resolution Compton profiles (CPs) from a Cu_{0.9}Al_{0.1} disordered alloy single crystal. The method was also applied to nine corresponding theoretical CPs computed within the K…
Abstract Blends of poly( L ‐lactic acid) (PLA) and poly(butylene succinate) (PBS) were prepared with various compositions by a melt‐mixing method and the phase behavior, miscibility, and morphology were investigated using differential scanning calorimetry, wide‐angle X‐ray diffraction, small‐angle X‐ray scattering tec…
We present Compton-scattering studies on the high-momentum components of the valence electron momentum density in beryllium. The experiments were performed with incident photon energies of 29 and 56 keV with a momentum space resolution of 0.10 and 0.16 a.u. units of momentum, respectively. The temperature dependence o…
INO has been active in microbolometer and FPA technology development since the early 1990s. Microbolometer detectors based on VO<SUB>2</SUB> films with TCR above 3% are typically fabricated. VO<SUB></SUB>x films with TCR above 2% have been developed for applications where FPA temperature is not stabilized. INO is cont…
We present a Raman scattering study of the ${\mathrm{La}}_{(2\ensuremath{-}x)/3}{\mathrm{Li}}_{x}{\mathrm{TiO}}_{3}$ $(0.1<~x<0.5)$ family of ionic conductors as a function of temperature, lithium content, thermal treatments, and isotope substitution, with the aim of elucidating the lithium location and dynamics…
We report on the sol–gel deposition and characterization of high-quality, epitaxial films of PbZr.52Ti.48O3 (PZT) on (001)Si substrates, with a thickness range of 400 Å to 1 μm. The epitaxial growth of PZT on (001)Si is achieved using a thin template layer of SrTiO3, grown by molecular-beam epitaxy. The sol–gel PZT fi…
We present a method to establish a correlation between the crystalline structure and the fluorescence properties of isolated semiconductor nanocrystals. By using ultrathin silicon nitride substrates with markers, we have localized and investigated the same particles in both a high-resolution transmission electron micr…
Carbon nitride films were grown on silicon and hard disk substrates using pulsed dc magnetron sputtering in a single-cathode deposition system. Substrates were mounted on a specially designed holder that allowed 45° tilt angle and substrate rotation about the surface normal up to 20 rpm. The influence of substrate bia…