Materials Literature
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The kinetics of degradation of methyl tert -butyl ether (MTBE) by ultrasonic irradiation in the presence of ozone as functions of applied frequencies and applied power are investigated. Experiments are performed over the frequency range of 205−1078 kHz. The higher overall reaction rates are observed at 358 and 618 kHz…
Two different approaches to the problem of carrier-induced ferromagnetism in the system of the disordered magnetic ions, one bases on self-consistent procedure for the exchange mean fields, other one bases on the RKKY interaction, used in present literature as the alternative approximations is analyzed. Our calculatio…
We have identified the pieces of the Fermi surface responsible for the long period oscillations of magnetic coupling across Cr and Cr$_{(1-x)}$V$_x$ alloy spacers in metallic multilayers. Analysing experiments and results of KKR-CPA calculations we find that the periods are determined by the extremal wave~vectors of t…
Results of a first-principles study of the Li impurity in GaN are presented. We find Li is a channel interstitial, with an onset for diffusion at T$\sim$ 600 K. Above this temperature, Li can transform to a Ga-substitutional acceptor by exothermic recombination with Ga vacancies. This process implies capture of at lea…
We review the theory of oscillatory magnetic coupling in Metallic Multilayers across alloy spacers. We illustrate the relationship between the frequencies of the oscillations and the extremal caliper vectors of the Fermi surface of the spacer by explicit calculations for Cu$_{(1-x)}$Ni$_x$, Cr$_{(1-x)}$V$_x$ and Cr$_{…
We study the response to shear of a one-dimensional monolayer embedded between two rigid plates, where the upper one is externally driven. The shear is shown to excite ``shearons'', which are collective modes of the embedded system with well defined spatial and temporal pattern, and which dominate the frictional prope…
<div class="section abstract"><div class="htmlview paragraph">Hydrogen has long been considered the fuel of the future. During this decade, significant resources have been invested in the development of advanced production, storage and utilization methods that hold the promise of moving society towards the…
Eine Kombination aus analytischen Methoden und Molecular-Modeling-Rechnungen ergibt ein detailliertes Bild der supramolekularen und mikroskopischen Struktur ausgefällter lipophiler Carotinoide. Die Nanopartikel sind aus einem Kern und einer Schale aufgebaut (siehe schematische Darstellung), wobei der Kern (120 nm) aus…
<div class="section abstract"><div class="htmlview paragraph">To achieve high thermal-to-electric energy conversion efficiency, it is desirable to operate thermoelectric generator devices over large temperature gradients and also to maximize the thermoelectric performance of the materials used to build the…
A combination of SiO vapor-deposition and direct wafer bonding is used to produce buried layers of SiOx. By thermally induced decomposition, Si nanocrystals embedded in SiO2 are obtained. Decomposition of the silicon suboxide is observed by studying the Si-O-Si stretching vibration in the infrared range. This phase se…
In this letter, we report on the influence of lead content on thin-film ferroelectric properties of lead niobium zirconate titanate. These films were prepared by the sol-gel technique and deposited on (La,Sr)CoO3 electrodes. It was determined that 7% excess lead in the sol was required to obtain nominally stoichiometr…
We have observed the ferroelectricity at room temperature in YMnO3 thin films prepared via solution. Precursor films of YMnO3 on Pt/sapphire or Y2O3/Si substrates were heat treated in vacuum or in air for controlling the crystallinity. X-ray diffraction measurements indicated that each film was a single phase of hexag…
Full chemical control of magnetic anisotropy in hexairon(III) rings can be achieved by varying the size of the guest alkali metal ion. Dramatically different anisotropies characterize the Li(I) and Na(I) complexes of [Fe(6)(OMe)(12)(L)(6)] (L=1,3-propanedione derivatives; a schematic representation of the Li(I) comple…
We positioned semiconducting multiwalled carbon nanotube, using an atomic force microscope, between two gold electrodes at SiO2 surface. Transport measurements exhibit single-electron effects with a charging energy of 24 K. Using the Coulomb staircase model, the capacitances and resistances between the tube and the el…
Mesoporous thin films based on neutral, porphyrin-bridged, tetrarhenium "square" compounds (metallacycles) display permeability to molecules smaller than the dimensions of an individual square cavity, but blocking behavior toward larger species (see schematic representation). The characteristic permeant size cutoff ca…
<div class="htmlview paragraph">Advanced thermoelectric microdevices integrated into thermal management packages and low power, electrical power source systems are of interest for a variety of space and terrestrial applications. By making use of macroscopic film technology, microgenerators operating across relat…
The dielectric susceptibility, = ´ - i ´´ , of nominally pure strontium titanate is measured between 4 and 70 K as a function of an external bias field. Static scaling analysis of the susceptibility reveals a very good scaling behaviour with a quasi-critical exponent a = /( - 1) = 2.00 ± 0.02 extracted consistently fr…
The ferroelectric SrBi2Ta2O9 (SBT) and YMnO3 buffer layers for the metal/ferroelectric/ insulator/semiconductor (MFIS) structure were deposited using pulsed-laser ablation and metalorganic chemical vapor deposition, respectively. Memory windows of the MFIS structure were in the range of 0.3–1.5 V when the gate voltage…
We study two expanded phases of Ge crystals, type-I (Ge 46 ) and type-II (Ge 136 ) clathrates, using an ab initio density functional planewave pseudopotential method. The equation of state, electronic structure and vibrational modes have been determined. These expanded Ge phases are shown to be only slightly higher in…
Building blocks for conducting polymers or NLO materials are the linear, unsaturated carbon chain bridged manganese complexes 1(n+) (n=0-2). All oxidation states were investigated spectroscopically and by X-ray structure determinations. The analytical data confirm a communication of the electrons over the C(4) chain-a…