Materials Literature
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${\mathrm{CrO}}_{2}$ cold-pressed powder compacts show different electronic transport property than the single crystals. We have analyzed the temperature dependence of the conductance and magnetoresistance (MR) of cold-pressed compacts of ${\mathrm{CrO}}_{2}$ powders. Our results show that there exist two channels of…
Experimental measurements are presented of the hole mobilities of four conjugated discotic systems, forming columnar liquid crystals, as a function of temperature. The measurements cover the crystalline/glassy phase and mesophase of these materials. It is a remarkable fact that the mobility is almost independent of te…
We present a first-principles study of the structure and quantum electronic conductance of junctions consisting of two crossed (5,5) single-walled carbon nanotubes. The structures are determined by constrained minimization of total energy at a given force between the two tubes, simulating the effects of substrate-tube…
Two-dimensional heterostructures have been exploited extensively in the synthesis of optoelectronic devices. Structures with small lattice mismatch can be synthesized readily. Large lattice mismatch in II–VI film heterostructures makes synthesis of devices with these materials more difficult. However, these large mism…
We show that the prediction of mode-coupling theory for a model of a network-forming strong glass former correctly describes the wave-vector dependence of the Debye-Waller factor. To obtain a good description it is important to take into account the triplet correlation function c(3), which we evaluate from a computer…
A bilayered quasiplanar metallic microstructure, comprising an ensemble of fully metallic “molecules” with inductive coupling between two parts of the molecule, is predicted to show strong optical rotatory power.
We have epitaxially grown Ba0.6Sr0.4TiO3 (BST-0.4) thin films on MgO(001) substrates. By inserting a very thin Ba1−xSrxTiO3 (x=0.1–0.7) interlayer between the MgO substrate and the main layer of BST-0.4, we are able to manipulate the degree of the stress in BST-0.4 films. We have controlled the stress states, i.e., th…
Optical absorption properties of n-type In-doped ZnO films were investigated by spectroscopic ellipsometry for varying carrier concentration. The fundamental optical band gap (E0) edge of the compound showed a blueshift below the carrier concentration n0=5×1019 cm−3, which can be explained in terms of the Burstein–Mos…
We report reactive Monte Carlo (RMC) simulations of reaction equilibria for both the nitric oxide dimerization and the ammonia synthesis reactions. We have applied the RMC technique to both a single bulk phase and also to a two-phase system, composed of the bulk gas and a slit-shaped pore, with pore parameters chosen…
We report a spectacularly high orbital/charge ordering temperature ${T}_{\mathrm{CO}}=475\mathrm{K},$ in ${\mathrm{Bi}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}.$ The charges order approximately $350\mathrm{K}$ above the temperature predicted by the bandwidth tuning mechanism in the ${\mathrm{Ln}}_{1/2}(\mathrm{C}\m…
A perturbation theory of the static response of insulating crystals to homogeneous electric fields, that combines the modern theory of polarization (MTP) with the variation-perturbation framework is developed, at unrestricted order of perturbation. First, we address conceptual issues related to the definition of such…
It is shown that the double-exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first-order transitions between phases with different electronic densities and/or magnetizations. The paramagnetic-ferromagnetic transition moves towards lower temperatures, and becomes discontinuous as th…
We present experimental data, numerical simulations, and analytical transfer-matrix calculations for a two-dimensionally isotropic, left-handed metamaterial (LHM) at X-band microwave frequencies. A LHM is one that has a frequency band with simultaneously negative εeff(ω) and μeff(ω), thereby having real values of inde…
ZnO nanowires were mass produced using a physical vapor deposition approach. The ZnO nanowire monocrystallites have an average diameter around 60 nm and length up to a few micrometers. The unidirectional growth of the ZnO nanowires was controlled by the conventional vapor-liquid-solid mechanism. Intensive UV light emi…
Influence of electron-electron relaxation processes on Auger recombination rate in direct band semiconductors is investigated. Comparison between carrier-carrier and carrier-phonon relaxation processes is provided. It is shown that relaxation processes are essential if the free path length of carriers doesn't exceed a…
The paper presents a comparative discussion of stress update algorithms for single-crystal plasticity at small strains. The key result is a new unified fully implicit multisurface-type return algorithm for both the rate-independent and the rate-dependent setting, endowed with three alternative approaches to the regula…
Quantum confinement effects on the optical properties of ion beam sputtered nickel oxide thin films are reported. Thin films with crystallite sizes in the range 9 to 14 nm have been deposited on to fused silica substrates. There is an increase in band gap, from 3.4 to 3.9 eV, and a decrease in refractive index, from 2…
In this paper we present a theoretical study of the linkage isomerization in [Co(NH 3 ) 5 ONO] 2+ . In particular, we have used for our analysis a hybrid density functional/Hartree−Fock method for the electronic computations (the so-called B3LYP), while a recent version of the polarizable continuum model has been cons…
Department of Fine Chemistry, Seoul National University of Technology, Seoul 139-743, KoreaReceived April 18, 2000Keywords: Porphyrin, Epoxidation, Hydroxylation, Oxoiron.Since the selective oxidations of hydrocarbons are ofimportance in both synthetic chemistry and industrial pro-cesses, biomimetic oxidation reaction…
Calcium phosphate precipitation obtained from aqueous solutions at room and body temperature and pH 5.5-7.5 were investigated by high-resolution transmission electron microscopy (HRTEM), transmission electron diffraction, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Supersaturated solutions of calci…