Materials Literature
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Materials with nanometric dimensions exhibit higher electrical resistivity due to additional scattering centers for the conduction electrons, mainly from surfaces and grain boundaries. In this study we focus on the effect of surfaces by implementing an experimental technique in which the resistivity of thin films is m…
In 2 O 3 heteroepitaxial layers of improved surface morphology and mobility were obtained by pulsed-laser-deposition method supplying proper oxygen to indium ratio on the growing surface, combined with the suppression of thermal decomposition of In2O3 layers. In situ monitoring of reflection high-energy electron diffr…
In this work, the hydrogen desorption and structural properties of the Li-Mg-N-H systems with different LiH/Mg(NH2)2 ratios are systemically investigated. The results indicate that the system with the LiH/Mg(NH2)2 ratio of 6/3 transforms into Li2NH and MgNH, and then, the mixture forms an unknown phase by a solid-soli…
Experimentally observed resonant absorption peaks in frequency dependent loss tangent in thin film parallel-plate SrTiO3 and Ba0.25Sr0.75TiO3 capacitors are explained by electrostriction and piezoelectric effects. A simple theory (linear approximation) is proposed to model the electric field and temperature dependence…
We propose a model of the blue-light-emitting center in silicon and silica-based materials on the basis of the density functional theory calculations. It has been shown that the dehydroxylation reaction involved in the annealing process of surface hydroxyl groups results in the formation of a defect pair consisting of…
Organisms, which grow on organic substrates that are metabolized via acetyl-CoA, are faced with the problem to form all cell constituents from this C(2)-unit. The problem was solved by the seminal work of Kornberg and is known as the glyoxylate cycle. However, many bacteria are known to not contain isocitrate lyase, t…
( Pb 0.97 Sr 0.03 ) ( Zr 0.05 Ti 0.95 ) O 3 nanocrystalline powder was prepared by a solution based chemical method. Preliminary x-ray diffractogram analysis of some aspects of crystal structure showed that a single-phase compound was formed exhibiting a tetragonal system. Impedance spectroscopy study showed the prese…
We have investigated the relation between the conduction property and the work function of the contact metal in carbon nanotube field-effect transistors (NTFETs). The conduction type and the drain current are dependent on the work function. In contrast to NTFETs with Ti and Pd contact electrodes, which showed p-type c…
Highly transparent, conducting, highly oriented, and almost single phase ZnO films have been deposited by simple e-beam evaporation method, and the deposition parameters were optimized. The films were prepared by (a) evaporation of ZnO at different substrate temperatures and (b) evaporation of ZnO at room temperature…
Thermionic emission from multiwalled carbon nanotubes (MWNTs) was investigated by using MWNT yarns. The work function of MWNT and thermionic emission constant of the yarn sample were both calculated from the thermionic emission data. The measured work function of MWNT is about $4.54--4.64\phantom{\rule{0.3em}{0ex}}\ma…
Research on the oxide perovskites has uncovered electronic properties that are strikingly enhanced compared with those in conventional metals. Examples are the high critical temperatures of the cuprate superconductors and the colossal magnetoresistance in the manganites. The conducting layered cobaltate $\rm Na_xCoO_2…
Raman spectra of (Mn, Co)-codoped ZnO films were investigated as functions of laser line and temperature. It is shown that the Raman shifts for different phonon modes exhibit redshift with temperature increasing, which can be attributed to the anharmonic effect in the material. Strong resonant Raman spectra of multi-L…
Bifunctional mesoporous material with an acidic framework and basic pores was synthesized via the co-condensation of TEOS, bistrimethoxysilylated precursors with a disulfide core, and 3-tert-butyloxycarbonyl (aminopropyl)triethoxysilane using P123 as surfactant; the reduction of disulfide units to SH groups followed b…
We use the self-interaction corrected local spin-density approximation to investigate the ground state valency configuration of transition metal (TM = Mn, Co) impurities in n- and p-type ZnO. We find that in pure Zn1-xTMxO, the localized TM2+ configuration is energetically favored over the itinerant d-electron configu…
We discuss the current status of the theory of the "high-temperature" superconductivity in intercalated graphites YbC6 and CaC6. We emphasize that while the general picture of conventional, phonon-driven superconductivity has already emerged and is generally accepted, there are still interesting problems with this pic…
Using SIEST-ART, a combination of the local-basis \textit{ab-initio} program SIESTA and the activation-relaxation technique (ART nouveau) we study the diffusion mechanisms of the gallium vacancy in GaAs. Vacancies are found to diffuse to the second neighbor using two different mechanisms, as well as to the first and f…
We report on optical spin pumping of modulation electrons in CdTe-based quantum wells with low intrinsic electron density (by 10^10 cm^{-2}). Under continuous wave excitation, we reach a steady state accumulated spin density of about 10^8 cm^{-2}. Using a two-color Hanle-MOKE technique, we find a spin relaxation time…
We introduce a simple solution-based method for the fabrication of highly oriented carbon nanotube (CNT) arrays to be used for thin-film transistors. We exploit the liquid-crystalline behavior of a CNT solution near the receding contact line during tilted-drop casting and produced long-range nematic-like ordering of c…
In situ TiB whisker reinforced Ti-4.0Fe-7.3Mo matrix composites have been fabricated by spark plasma sintering (SPS). The microstructure of the in situ TiB whiskers and interfacial structures in the composites were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-res…
We study the problem of Dirac fermion confinement in graphene in the presence of a perpendicular magnetic field $B$. We show, analytically and numerically, that confinement leads to anomalies in the electronic spectrum and to a magnetic-field-dependent crossover from $\sqrt{B}$, characteristic of Dirac-Landau-level be…