Materials Literature
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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…
Chromium dioxide (CrO2) films have been grown epitaxially on (100) TiO2 substrates using chemical vapor deposition and their magnetic properties were studied as a function of film thickness (500 Å–1.2 μm). Because of the lattice mismatch with the substrate, the films are strained as evidenced by x-ray diffraction meas…
Single-walled carbon nanotubes are synthesized by chemical vapor deposition of methane at controlled locations on a substrate using patterned catalytic islands. The combined synthesis and microfabrication technique presented here allows a large number of ohmically contacted nanotube devices with controllable length to…
<div class="section abstract"><div class="htmlview paragraph">The daily variation in air temperature is large compared with the temperature changes a short distance below the surface of the ground. In theory, a heat engine can be arranged to produce electricity from this temperature difference. In practice…
We have performed an angle-resolved photoemission study on untwinned PrBa$_2$Cu$_3$O$_7$, which has low resistivity but does not show superconductivity. We have observed a dispersive feature with a band maximum around ($π$/2,$π$/2), indicating that this band is derived from the undoped CuO$_2$ plane. We have observed…
We have studied the chemical potential shift in La$_{2-x}$Sr$_x$NiO$_4$ and the charge ordering transition in La$_{1.67}$Sr$_{0.33}$NiO$_4$ by photoemission spectroscopy. The result shows a large ($\sim$ 1 eV/hole) downward shift of the chemical potential with hole doping in the high-doping regime ($δ\gtrsim$ 0.33) wh…
The dielectric response of many materials exhibits universal behavior in the form of a power law frequency dependence of the ac conductivity. This response is seen in all types of structures both crystalline and amorphous and for all types of polarizing species including dipoles and ions. Here I demonstrate that for i…
Abstract Disordered or ‘glassy’ materials are of significant technological value. Their structure can be investigated by diffraction (neutron, X-ray, electron) techniques. When the available volume is very small (eg thin films, non-homogeneous structures) only electrons are suitable. Cockayne and McKenzie developed a…
In narrow-band conductors a weakly screened Coulomb interelectron repulsion can supress narrow-band electrons’ hopping, resulting in formation of a “frozen” electron phase which differs principally from any known macroscopic self-localized electron state including the Wigner crystal. In a zero-band-width limit the “fr…
A discontinuity wall in smectic A liquid crystals was discussed in M. Kléman, Points, Lines and Walls in Liquid Crystals, Magnetic Systems and Various Ordered Media (J. Wiley. Chichester 1983). Possible solutions describing a twist disclination which terminates the discontinuity wall in an infinite smectic A liquid cr…
The synthesis of meso-tetraphenylporphyrin (TPP) and its application in a solar- energy conversion device are described as an undergraduate laboratory experiment. In the first part of the exercise, a convenient procedure for the synthesis of TPP is presented. In the second section of the experiment, the construction o…
Abstract The electrical properties of SrTiO3 (strontium titanate) ceramics are strongly influenced or even dictated by grain boundary segregation of charged point defects, such as dopant atoms, impurities, vacancies, or self-interstitials. The atomistic structure of the grain boundaries, their energy, and the segregat…
Abstract Quantitative analysis with the electron microprobe analyzer (EMPA) has yielded more accurate results over time as a result of improvements in ZAF and other correction routines, mass absorption coefficients, synthetic pseudocrystals for ultralight elements, computers, software programs, backscattered electron…
Abstract A comprehensive understanding of the relation between structure and properties in nano-materials calls for an extensive knowledge of the adhesion between nanoparticles. Electron diffraction contrast from the stress field caused by adhesion between contacting particles yields a detailed information on surface…
Based on complex electro-optical and dielectric measurements, the processes of low frequency relaxation in PDLC (Polymer Dispersed Liquid Crystals) films have been studied. Experimental data are presented to investigate PDLC structure and its evolution with increase in LC concentration. These results are found to be i…
This chapter contains sections titled: Introduction Experimental Procedures Results and Discussion Conclusions Acknowledgements
The dependence of the cellular (biogenic) and frustule-associated (mineralized) silica content of the diatoms Navicula salinarum and Thalassiosira weissflogii on salinity and aluminium conditions was studied in order to make it possible to manipulate silicification in vitro and maximize it to levels required for physi…
The texture changes during the initial phase of blanching of potatoes, carrots and green peas at different blanching times (0–240 s) and temperatures (85 °C, 95 °C, 100 °C) were investigated. The breaking force (N) was determined by compression or Back extrusion tests with an Instron texture tester. Electronmicroscopi…