Materials Literature
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We present electro-optical experiments in ferroelectric freely suspended smectic films using reflective polarizing microscopy. The observation of travelling 180° walls (kinks) in the film plane is described. The c-director alignment at the lateral film boundaries initiates the kink formation when the polarity of an ex…
It has been found that the formation of a ferroelectric phase for the SrBi 2 Ta 2 O 9 (SBT) thin films derived from sol–gel solution is dependent on the oxygen pressure during the heat-treatment process. Under an elevated oxygen pressure as high as 30 atm, the heat-treatment temperature inducing the ferroelectric SBT…
Effects of a DC field on the real part of the relative dielectric constant of Al 2 O 3 -doped barium strontium titanate for application in phased array antennas have been studied. The real part of the relative dielectric constant of the specimens decreases when the applied DC field is increased. The tunability is abou…
The ultrasonic velocity, viscosity, refractive index and density of polycarbonate/poly-(methyl methacrylate) (PC/PMMA) and polycarbonate/polystyrene (PC/PS) blends in solution have been measured at 30°C. Using the viscosity data, the interaction parameters have been computed which indicate that the PC/PMMA blend is mi…
Poly(3-methylthiophene) (P3MT) films were electrogenerated on both platinum and carbon-felt working electrodes. The kinetic equation was determined by the monomer and electrolyte concentrations being changed for different reaction times. For each sample, the weight of the polymer obtained was measured along with the p…
A new type of cyanide-bridged bimetallic assemblies, [Ni(chxn)2]3[M(CN)6]2·2H2O (chxn = 1,2-trans-cyclohexanediamine; M3+ = Fe (1), Co (2)), have been prepared. The X-ray crystallography for the assemblies has proved a 2-D network comprised of M6Ni6 dodecagon units extended by M-CN-Ni linkage. Compound 1 shows a ferro…
Well-aligned pseudosingle crystals of a series of Terfenol-D and Al-substituted alloys have been prepared using the Czochralski method, a route that has the advantage that a grain-aligned rod can be prepared in one relatively speedy operation. The effects of several factors, including pulling rate, heat treatment, and…
Ternary thallinm lanthanide dichalcogenides TILnX2 (X = S, Se, or Te; Ln = lanthanide, except Ce and Pr) crystallize in the rhombohedral structure of -NaFeO 2 type (R3m). Their crystal lattice consists of the layers of Ln3 + ions separated by three layers of the non-magnetic ions (-Ln-X-Tl-X-Ln-). The magnetization wa…
The feasibility and a review of progress in the long-wavelengths anomalous dispersion technique is given in the context of the development of beamline ID1 of the ESRF for such studies. First experiments on this beamline and their analyses are described. The first study reports on the use of uranium which exhibits an u…
In a number of nitrogen-fixing bacteria, nitrogenase is posttranslationally regulated by reversible ADP-ribosylation of dinitrogenase reductase. The structure of the dinitrogenase reductase from Azotobacter vinelandii is known. In this study, mutant forms of dinitrogenase reductase from A. vinelandii that are affected…
We fabricated field-emission vacuum microelectronic devices such as diode and triode devices, using high-resolution electron-beam lithography in combination with the reactive ion etching (RIE) technique. The turn-on voltage of the diode is 13 V, which is the lowest value reported for single-crystalline lateral silicon…
We investigated the behaviour in tension and at room temperature of TiNi shape memory alloys in martensitic state. Our first experimental results show that two deformation mechanisms are involved in the behaviour of such materials: martensite platelets reorientation and irreversible plasticity. Moreover when irreversi…
Periodic domain patterns have been observed in a nematic liquid crystal cell induced by an elastic wave which propagates on a glass plate over a wide frequency range. The frequency dependence of the periodic length of the domain pattern is measured and a numerical analysis of elastic wave propagation is carried out in…
Abstract We report the long‐term stability and improved brightness and efficiency of the brightest known non‐filtered EL phosphor Ga 2 O 3 : Eu. A high brightness of 840 cd/m 2 is maintained for a single‐insulating device for over 2500 hours at 370V/650 Hz. We demonstrate the inherent stability of the rf sputtered dev…
Perovskite-type Nd0.7Bao0.3MnO3 has been synthesized and its magnetic and magnetotransport properties studied in the temperature range from 5 K to 300 K. X-ray diffraction indicates that the crystal-symmetry is orthorhombic with a=0.5508(1) nm, b=0.5496(2) nm, and c=0.7764(3) nm. There exist two magnetic phase transit…
The crystal structure of the mesoionic compound 2-oxo-3-benzoyloxazolo[3,2-a]pyridine (C 14 NO 3 H 9 ) has been determined from X-ray powder data using the grid search procedure. The crystal symmetry is orthorhombic (space group Pna2 1 , a=7,940(1) Å, b=24,562(3) Å, c=5,402(1) Å). The results of Rietveld refinement (R…
The present study describes the fabrication and characterization of cluster diamond (CD) dispersed Cu composites. A powder metallurgy method combining mechanical milling and hot pressing was used to produce CD dispersed Cu composites. The Cu matrix powders and CD were mechanically milled at 500 rpm in an Ar atmosphere…
In this paper we report on the synthesis and characterization of new mixtures of achiral liquid crystalline side-chain polymers with their monomers. The samples have a basic structure similar to materials prepared earlier showing antiferroelectric behaviour. They are investigated to study the influence of peculiar dif…
Polycrystalline Al 2 O 3 ceramics doped with Cr (sintered ruby) up to high concentrations (0.66, 0.76 and 0.97 wt%) were fabricated with an extrusion molding process using Al 2 O 3 and Cr 2 O 3 powders. It was found from absorption spectra that a high concentration of Cr ions was optically activated. The fluorescence…
We show that the Barkhausen avalanches exhibit power law distributions and scaling exponents belonging to two distinct universality classes. We explain these results in terms of the critical behavior of the domain wall at the depinning transition, with exponents set by the long-range dipolar interactions arising from…