Materials Literature
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The structure and chemistry of two electrical trees (designated Tree A and Tree B) grown in low density polyethylene have been studied by a combination of confocal Raman microprobe spectroscopy, optical microscopy and scanning electron microscopy. Despite being grown under similar conditions (A, 30 °C and 13.5 kV; B,…
We fabricated B2-ordered Co 2 MnAl and L2 1 -ordered Co 2 MnSi Heusler alloy films by optimizing various fabrication conditions (substrate, composition of sputtering target, substrate and post-annealing temperature, etc) and applied these films to bottom electrodes of magnetic tunnel junctions (MTJs). We used Al-oxide…
We studied the magnetization losses of four different types of filamentary YBCO coated conductors. A 10 mm wide YBCO coated conductor was subdivided into 20 filaments by laser cutting. The separation of coupling loss from the total is possible because the energy loss per cycle in samples with electrically insulated fi…
Alle Farben des Regenbogens können bei Anregung eines Zeolithkristalls beobachtet werden, der unterschiedliche Mengen an Eu3+- und Tb3+-Ionen sowie ein Sensibilisatormolekül (Benzophenon oder 4-Acetylbiphenyl) in seiner Gerüststruktur enthält (siehe Bild). Die Farben lassen sich durch Variation der Mengen der drei Kom…
Abstract Linear and branched poly(butylene adipate)s (PBA) with molecular weights ranging from 2000 to 10,000 g/mol, and a branching agent content between 0 and 1.8%, were solution cast with poly(vinyl chloride) (PVC) to form 50‐ to 60‐μm thick flexible films. Dry films were analyzed by tensile testing, Fourier transf…
Metamaterial structures designed to have simultaneously negative permittivity and permeability are known as left-handed materials. Their complexity and our understanding of their properties have advanced rapidly to the point where direct applications are now viable. We present a radial gradient-index lens with an inde…
All the colors of the rainbow can be observed upon excitation of a zeolite crystal incorporated with varying quantities of Eu3+ and Tb3+ ions as well as a sensitizer molecule (benzophenone or 4-acetylbiphenyl) in its framework structure (see picture). The colors can be fine-tuned by varying the amounts of the three co…
The astronomical number of accessible discrete chemical structures makes rational molecular design extremely challenging. We formulate the design of molecules with specific tailored properties as performing a continuous optimization in the space of electron-nuclear attraction potentials. The optimization is facilitate…
We use the fractional integrals to describe fractal media. We consider the fractal media as special ("fractional") continuous media. We discuss the possible experimental testing of the continuous medium model for fractal media that is suggested in Phys. Lett. A. 336 (2005) 167-174. This test is connected with measure…
Coupling of spin states and space motion of conduction electrons due to spin-orbit interaction opens up possibilities for manipulation of the electron spins by electrical means. It is shown here that spin orientation of a two-dimensional electron gas can be achieved by excitation of the carriers with a linearly polari…
The contrast mechanism for the visualization of ferroelectric domain boundaries with lateral force microscopy is generally assumed to be caused by mechanical deformation of the sample due to the converse piezoelectric effect. We show, however, that electrostatic interactions between the charged tip and the electric fi…
MoSi2 doped MgB2 tapes with different doping levels were prepared through the in-situ powder-in-tube method using Fe as the sheath material. Effect of MoSi2 doping on the MgB2/Fe tapes was investigated. It is found that the highest JC value was achieved in the 2.5 at.% doped samples, more than a factor of 4 higher com…
A theory of electron spin relaxation in semiconducting carbon nanotubes is developed based on the hyperfine interaction with disordered nuclei spins I=1/2 of $^{13}$C isotopes. It is shown that strong radial confinement of electrons enhances the electron-nuclear overlap and subsequently electron spin relaxation (via t…
We show that the tunable hybridization between two lateral quantum dots connected to non-magnetic current leads in a `hanging-dot' configuration that can be used to implement a bipolar spin filter. The competition between Zeeman, exchange interaction, and interdot tunneling (molecular hybridization) yields a singlet-t…
The time evolution of optically excited carriers in semiconductor quantum wells and quantum dots is analyzed for their interaction with LO-phonons. Both the full two-time Green's function formalism and the one-time approximation provided by the generalized Kadanoff-Baym ansatz are considered, in order to compare their…
Ordered porous carbon with tailored pore size represents an innovative concept in electrochemical hydrogen storage. This work deals with physical characteristics and electrochemical hydrogen storage behavior of the ordered porous carbons with well-tailored pore size, synthesized by a replica technique using hexagonal…
We have investigated the structure and magnetization of Co2(Cr1−xFex)Al (0 ≤ x ≤ 1) and Co2FeSi full-Heusler alloy films deposited on thermally oxidized Si (SiO2) and MgO (001) single crystal substrates by ultra-high vacuum sputtering at various temperatures. The films were also post-annealed after deposition at room…
Quaternary Heusler alloys Co$_2$Cr$_{1-x}$Fe$_{x}$Al with varying Cr to Fe ratio $x$ were investigated experimentally and theoretically. The electronic structure and spectroscopic properties were calculated using the full relativistic Korringa-Kohn-Rostocker method with coherent potential approximation to account for…
Half-Heusler compounds XYZ. also called serni-Heusler compounds, crystallize in the C1(b) MgAgAs structure, in the space group F (4) over bar 3m. We report a systematic examination of band gaps and the nature (covalent or ionic) of bonding in semiconducting 8- and 18-electron half-Heusler compounds through first-princ…
Fine particles of lithium ferrite were synthesized by the sol-gel method.By subsequent heat treatment at different temperatures, lithium ferrites of different grain sizes were prepared.A structural characterization of all the samples was conducted by the x-ray diffraction technique.A grain size of around 12 nm was obs…