Materials Literature
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Abstract In this study, the melting behavior of isothermally crystallized polytri‐ methylene terephthalate (PTT) was investigated. Multiple melting behaviors in DSC heating trace were found because two populations of lamellar stacks were formed during primary crystallization and the recrystallization at heating proces…
The first successful deposition of mesoporous vanadium oxide films and their application as high-rate cathode materials for lithium batteries are described in this communication. The novel electrochemical deposition process developed for the preparation of these films makes use of non-ionic surfactant templates. The F…
Using a combination of experimental techniques, we show that Cu(II) reduction by sulfide to Cu(I) occurs in solution prior to precipitation. EPR and 63Cu NMR data show that reduction to Cu(l) occurs during the reaction of equimolar amounts of Cu(II) with sulfide. 63Cu solution NMR data show that Cu(I) is soluble when…
Crystalline silver nanowire arrays (see Figure) with high aspect ratio are produced here by electrodeposition from a reverse hexagonal liquid-crystalline phase. Enhancement of the alignment is shown to be possible by applying a high electric field gradient during deposition. High-density bundles can be obtained by was…
A new tetragonal (P42(1)2) crystalline form of [Cr8F8Piv16] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the unit cell, form almost perfectly planar, regular octagons. The interaction between the CrIII ions is antiferromagnetic (J = 12…
Conductive polyaniline nanowires in emeraldine form can be deposited by potentiodynamic electropolymerization from a reverse hexagonal liquid crystalline phase where one-dimensional (1D) aqueous channels can serve as space-confined reactors. Polyaniline nanowire bundles with single-wire diameter of 50–70 nm and length…
In most electronic devices, electric current of both types (electrons and holes) flows through a junction. Usually the boundary conditions have been formulated exclusively for open circuit. The boundary conditions proposed here bypass this limitation by the first time, as far as we are aware. Besides, these new bounda…
The DC transport properties and microwave absorption (at 41 GHz) are measured in a bulk ceramic sample and a film (220 nm thick) of La$_{0.5}$Sr$_{0.5}$CoO$_{3-δ}$. The samples are polycrystalline. The microwave conductivity, which is related mainly to the intragrain conductivity, increases by the order of the magnitu…
Recently the scaling laws describing the roughness development of fracture surfaces was proposed to be related to the macroscopic elastic energy released during crack propagation [Mor00]. On this basis, an energy-based asymptotic analysis allows to extend the link to the nominal strength of structures. We show that a…
The magnetization in a magnetic microdot made from soft magnetic materials can have a vortex-like ground state structure resulting from competition between the exchange and dipolar interactions. Normal mode magnon frequencies for such dots are calculated taking into account both exchange and magnetostatic effects. The…
Abstract Rice husk ash is mainly composed of silica and carbon black remaining from incomplete combustion. Both silica and carbon black have long been recognized as the main reinforcing fillers used in the rubber industry to enhance certain properties of rubber vulcanizates, such as modulus and tensile strength. In th…
Large, monodisperse core-shell Au-Ag nanoparticles with Ag-like optical properties have been prepared by the seeding growth method in micellar media.
Novel electrochemical transistors, based on the conductive polymer PEDOT, operating at driving voltages of only a few volts in bulk material, and with little demand on substrate planarity, are described by the authors. The underlying polymer ion pair PEDOT:PSS is conductive in both oxidized and reduced state. Two tran…
Carbon capsules with hollow core/mesoporous shell (HCMS) structures have been synthesized (see Figure for schematic) for the first time using solid core/mesoporous shell (SCMS) silica spheres as templates. The capsules have bimodal pore systems consisting of a uniform, tunable, hollow macroscopic core and a mesoporous…
A simple synthesis of high-quality Cu2O, a material of high interest in optics because of its photon exciton interconversion properties, in the form of nanowires (see Figure for a TEM image) is reported by the authors. Reduction of Cu(OH)2, freshly prepared from CuCl2, with hydrazine hydrate in basic solution in the p…
Nanowalls, a new nanostructural morphology of carbon, grow instead of nanotubes under microwave plasma-enhanced CVD conditions on substrates electrically disconnected from the lower electrode. While not fully understood, the formation of nanowalls (see Figure for top view) appears to depend on the local electric field…
Existing phenol production processes tend to be energy-consuming and produce unwanted by-products. We report an efficient process using a shell-and-tube reactor, in which a gaseous mixture of benzene and oxygen is fed into a porous alumina tube coated with a palladium thin layer and hydrogen is fed into the shell. Hyd…
Properties of materials determined by their size are indeed fascinating and form the basis of the emerging area of nanoscience. In this article, we examine the size dependent electronic structure and properties of nanocrystals of semiconductors and metals to illustrate this aspect. We then discuss the chemical reactiv…
Semiconductors and metals exhibit unusual optical, electronic, and magnetic properties on the nanometer scale. Chemists and materials scientists are developing methods to make non-spherical shapes of semiconductors and metals on the nanometer scale. We use a seed-mediated growth approach to make metallic nanorods and…
We investigate the properties of classical single flip dynamics in sets of two-dimensional random rhombus tilings. Single flips are local moves involving three tiles which sample the tiling sets via Monte Carlo Markov chains. We determine the ergodic times of these dynamical systems (at infinite temperature): they gro…