Materials Literature
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The density of states and one-particle spectral function $A(\mathbf{k},\ensuremath{\omega})$ of the one- and two-orbital models for manganites, the latter with Jahn-Teller phonons, are evaluated using Monte Carlo techniques. Unexpectedly robust pseudogap (PG) features were found at low and intermediate temperatures, p…
We argue that the charge ordering observed in $50%$ doped manganites is a manifestation of the peculiar antiferromagnetic spin ordering. The latter, combined with the large Hund's rule physics in manganites, divides the whole system into the quasi-one-dimensional zigzag objects, which exhibit a very unique electronic…
Silica thin films containing Si nanocrystals and Er3+ were prepared by ion implantation. Excess Si concentrations ranged from 5% to 15%; Er3+ concentration for all samples was 0.5%. Samples exhibited photoluminescence at 742 nm (attributed to Si nanocrystals), 654 nm (defects due to Er3+ implantation), and at 1.53 μm…
Liberation of the ligand from the nickel complex 1 obtained by template synthesis yielded isoporphycene (as the octaethyl derivative 2), the first constitutional isomer of porphyrin with an N(4) core for which E/Z isomerism is involved: Compound 2 is present as the E isomer, which is in rapid, presumably acid-catalyze…
Amplifying planar waveguide structures in Er-doped nanocrystalline II/VI semiconductor layer systems were developed by photolithography and wet chemical etching. 2 μm thick planar waveguides on glass substrates with lateral dimensions down to 5 μm with rectangular cross section were realized. By optical excitation a m…
In contrast to the binary switchable mirror films (YHx, LaHx, REHx with RE:rare earth) which have a weak red transparency window in their metallic dihydride phase, rare-earth alloys containing magnesium are remarkable for the large contrast between their metallic dihydride and transparent trihydride phase. By means of…
Numerical calculations reveal that the target and spiral growth patterns in spherulites can be generated from the time-dependent Ginzburg-Landau equations (model $C$) by coupling a conserved compositional order parameter and a nonconserved crystal ordering parameter. Of particular interest is that the periodic concent…
Semipermeable nanoscopic hollow spheres or cages with diameters in the sub-micrometer to the 100 nm range are accessible by the self-assembly of polymers onto sub-micrometer sized particles (Möhwald et al.) or by the formation of shell-cross-linked polymeric micelles (Wooley et al.) followed by chemical degradation of…
Carbon nanotubes (CNTs), standing perpendicularly to a substrate with an electrode, were fabricated by thermal catalytic decomposition of ethylene from Co particles electrochemically embedded at the bottom of anodic alumina nanoholes. The thermal durability of the alumina nanoholes for the CNTs growth process was achi…
A combination of postsynthesis grafting and hydrothermal treatment offers an excellent route for the synthesis of ultrastable mesoporous aluminosilicates with enhanced acidity and catalytic activity. The stability observed (>150 h in boiling water; 4 h at 1000 degrees C) is, for mesoporous silicates, remarkable. Unusu…
Highly ordered multiwalled carbon nanotube arrays have been fabricated by using porous anodic alumina templates prepared by a two-step anodization process. Nanotubes were very uniform in diameter. Two-dimensional tube arrays were highly ordered within domain boundaries, and their vertical alignment was nearly perfect.…
Exact planarity at the central carbon atom is achieved, according to molecular orbital calculations, in the strained polycyclic cage hydrocarbon dimethanospiro[2.2]octaplane (see structure). There are no glaringly long C-C bonds, which might have reflected inherent instability in this molecule that is yet to be synthe…
Many properties of alloyed chalcogenide glasses can be closely correlated with the average coordination of these compounds. This is the case, for example, of the ultrasonic constants, dilatometric softening temperature and the vibrational densities of states. What is striking, however, is that these properties are nev…
It has been recently shown that precipitation bands characteristic of Liesegang patterns emerge from spinodal decomposition of reaction products in the wake of moving reaction fronts. This mechanism explains the geometric sequence of band positions x_n ~ Q(1+p)^n and, furthermore, it yields a spacing coefficient, p, t…
Structure optimizations were performed for 1 and 2 monolayers (ML) of Fe on a 5 ML W(110) substrate employing the all-electron full-potential linearized augmented plane-wave (FP-LAPW) method. The magnetic moments were also obtained for the converged and optimized structures. We find significant contractions ($\sim$ 10…
Using spin dynamics simulations we predict the splitting of the longitudinal spin wave peak in all antiferromagnets with single site anisotropy into two peaks separated by twice the energy gap at the Brillouin zone center. This phenomenon has yet to be observed experimentally but can be easily investigated through neu…
A luminescence pulse has been observed from a laser-created bubble in liquid nitrogen and liquid argon at the first collapse point of the bubble. An unusual feature is that the width of the pulse is of order 100-1000 ns, much longer than the 2-8 ns pulses observed when the same experiment is carried out with a water s…
Barium strontium titanate thin films are being developed as capacitors in dynamic random access memories. These films, grown on silicon substrates, are under tensile residual stress. By a converse electrostrictive effect, the in-plane tensile stress reduces the capacitance in the thickness direction of the film. We me…
We investigate the thermal conductivity of silicon nanowires based on molecular dynamics (MD) simulations. The simulated thermal conductivities of nanowires with square cross sections are found to be about two orders of magnitude smaller than those of bulk Si crystals in a wide range of temperatures (200–500 K) for bo…
Surface tension of the polyacrylamide solution was measured as a function of the polyacrylamide concentration (0–1000 gm/m3) and temperature (10–60°C). The static contact angles of the polyacrylamide solutions in the range of 0–1000 gm/m3 were reported on the polyvinyl chloride and Teflon substrates. Surface tension,…