Materials Literature
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The correlation between the structural (average size and density) and optoelectronic properties [band gap and photoluminescence (PL)] of Si nanocrystals embedded in SiO2 is among the essential factors in understanding their emission mechanism. This correlation has been difficult to establish in the past due to the lac…
Dense ceramic composites consisting of two phases, ferroelectric BaTiO3 and ferrite (Ni0.3Zn0.7)Fe2.1O4, were synthesized via the solid state reaction route. The results indicate that insulating BaTiO3 can be well compatible to the conductive phase (Ni0.3Zn0.7)Fe2.1O4. The electrical conduction and dielectric behavior…
We present an interpretation of the x-ray absorption spectra of arsenic chalcogenide glasses, As4Se4 and As2Se3, from a first-principles calculation. Our calculation identifies the atomistic origins of the observed photoemission data. The importance of structural "building blocks" present in a particular glass to the…
Formulation of the Fourier modal method for multilevel structures with spatially adaptive resolution is presented, using a slightly reformulated representation for the spatial coordinates. Projections to Fourier base in boundary value problem are used allowing extensions to multilayer profiles with differently placed…
A generalized theoretical approach of the transverse susceptibility, χT, in the case of uniaxial ferromagnets is presented. This advances the classical model of transverse susceptibility where only the first-order anisotropy constant, K1, is taken into account and makes possible the study of the influence of the secon…
Spectral dependence of two-photon absorption in a chalcogenide glass, As2S3, has been studied using a tunable light source. The result shows that two-photon and two-step absorptions occur, and the two-photon absorption spectrum appears to be exponential. These results and roles of nonlinear processes in photoinduced p…
We consider the $t\ensuremath{-}J$ model for doped manganites, and show that double exchange for correlated ${e}_{g}$ electrons favors in the ferromagnetic metallic phase an orbital liquid (i.e., orbital-disordered) state. Therefore the spin-wave stiffness is isotropic, and increases with hole doping x, providing a di…
We have employed the quartz-crystal microbalance technique to measure the sliding friction of krypton films physisorbed on gold. By slowly increasing the amplitude of the substrate oscillations, we have observed a sharp transition from a film locked to the substrate to a sliding one. This transition is characterized b…
Branching structure in carbon nanotubes (CNT) are of great importance in developing CNT-based mechanical or electrical applications. For this purpose, CNTs exhibiting two-dimensional and three-dimensional junctions are being sought. Among them, only two-dimensional branching structures of Y-junction and T-junction CNT…
Based on epitaxial layer transfer silicon on insulator wafers, crystalline Si/SiO2 quantum wells have been made. The chemical composition of the quantum wells was studied by Auger electron spectroscopy depth profile. The crystalline structure of the well was confirmed by x-ray photoelectron diffraction. Band-edge shif…
We calculated with ab initio methods the in-plane phonon deformation potentials of a graphite sheet. The two-dimensional Gr\"uneisen parameter is found to be $\ensuremath{\gamma}=2.0$ and the shear potential $(\mathrm{SDP})=0.66.$ The two values agree well with experimental results on graphite and on carbon nanotubes.
Nanostructured h-BN was prepared by mechanical milling under hydrogen atmosphere. The hydrogen concentration reaches up to 2.6 mass% after milling for 80 h, and this value corresponds to ca. 35% of that of nanostructured graphite as was previously reported. In addition to the hydrogen desorption starting at about 570…
1-Allyl-3-propylthiourea modified mesoporous silica has high adsorption capacity for mercury ions and its regeneration can be accomplished by washing with 10% thiourea in aqueous 0.05 M HCl.
β- PbO 2 nanobelts, with a rectangular cross section, a typical length of 10–200 μm, a width of 50–300 nm, and a width-to-thickness ratio of 5–10, have been successfully synthesized by simple elevated evaporation of commercial PbO powders at high temperature. The PbO2 nanobelts are enclosed by top surfaces ±(201) and…
We applied the recently developed technique of force-detected nuclear magnetic resonance (NMR) to observe 71Ga, 69Ga, and 75As in GaAs. The nuclear spin-lattice relaxation time is 21$\pm$5 min for 69Ga at $\sim 5$ K and 4.6 Tesla. We have exploited this long relaxation time to first create and then observe spatially v…
The validity of fluctuation dissipation relations in an aging system is studied in a colloidal glass during the transition from a fluid-like to a solid-like state. The evolution of the rheological and electrical properties is analyzed in the range $1Hz - 40Hz$. It is found that at the beginning of the transition the f…
The effects of cell adhesion peptides (RGDS, KQAGDV, VAPG) on vascular smooth muscle cells grown on modified surfaces and in tissue-engineering scaffolds were examined. Cells were more strongly adhered to surfaces modified with adhesive ligands than to control surfaces (no ligand or a nonadhesive ligand). Cell migrati…
The structure of ZnO quantum dots prepared via the wet chemical method was studied. By introducing an annealing treatment (150 °C–500 °C), we also investigated the effect of the change in the structure of the dots on their luminescence properties. Our studies revealed that the surface of the as-prepared dots is passiv…
*Reprinted from Functional Monomers and Polymers, 2nd ed.; Takemoto, K., Ottenbrite, R.M., Kamachi, M., Eds.; Marcel Dekker, Inc.: New York; 1997, 149–171.
Al–Cu–Fe alloys were prepared from elemental powders in a high-energy planetary ball mill. A sequence of solid state reactions resulting in quasicrystal (QC) phase formation takes place during heating of the as-milled powder. These reactions were studied by both differential scanning calorimetry and x-ray diffraction…