Materials Literature
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Impurities play a major role in determining the optical and electrical properties of semiconductor nanoparticles. In this work, the presence and source of CO2 impurities in ZnO nanoparticles were studied by IR absorption spectroscopy. Isotopic substitution was used to verify the vibrational frequency assignment. Isoch…
We report on a simple and low-cost route to produce SiC nanotubes without the need for the more usual oxide based reactions using a high temperature substitution reaction between multiwall carbon nanotubes as a frame and Si powder. Local scale studies using transmission and scanning electron microscopy are also presen…
In this paper we report results for magnetic observables of finite spin clusters composed of $S=1∕2$ ions. We consider clusters of two, three, and four spins in distinct spatial arrangements, with isotropic Heisenberg interactions of various strengths between ion pairs. In addition to the complete set of energy eigenv…
We have developed bond additivity correction (BAC) procedures for the G3-based quantum chemistry methods, G3B3 and G3MP2B3. We denote these procedures as BAC-G3B3 and BAC-G3MP2B3. We apply the procedures to compounds containing atoms from the first three rows of the periodic table including H, B, C, N, O, F, Al, Si, P…
This paper demonstrates the rapid and precise size selection of nanoparticle populations using the pressure tunable solvent properties of CO2-expanded liquids. Specifically, by pressurizing and expanding a single organic solution with carbon dioxide gas, ligand-stabilized silver particles of desired mean size were siz…
This account describes the synthesis of ordered mesoporous solids via a nanocasting pathway, using porous silica and porous carbon as hard templates. Non-siliceous mesoporous materials with new compositions, controllable structure, and specific functionality can be created. Structure replication on the length scale of…
Structural effects of chain extender on phase mixing and coating properties of polyether-based moisture-cured polyurethane ureas (MCPUs) were determined with a polytetramethylene glycol (PTMG-1000), trimethylol propane (TMP), and isophorone diisocyanate (IPDI)-based system. The reaction of PTMG/TMP/IPDI was carried ou…
A densely packed granular system is an example of an out-of-equilibrium system in the jammed state. It has been a longstanding problem to determine whether this class of systems can be described by concepts arising from equilibrium statistical mechanics, such as an effective temperature and compactivity. The measureme…
High-resolution x-ray diffraction and transmission electron microscopy (TEM) have been used to study BiFeO3 thin films grown on the bare and SrRuO3 buffered (001) SrTiO3 substrates. Reciprocal space mapping (RSM) around (002) and (103) reflections revealed that BFO films with a thickness of about 200 nm were almost fu…
The crystal structure and thermodynamic stability of a number of proposed models for the inclusion of Ti in $\mathrm{Na}\mathrm{Al}{\mathrm{H}}_{4}$ have been calculated by employing density functional theory in the generalized gradient approximation. It was shown that the least unfavorable location of Ti is close to…
Vertical emulsion films with particle monolayers at their surfaces have been studied by direct microscope observations. The effects of particle wettability and surface coverage on the structure and stability of water films in octane and octane films in water have been investigated. Monodisperse silica particles (3 mic…
The Cordillera Huayhuash is a north‐south‐oriented range along the drainage divide of the northern Peruvian Andes. The range has high topography with peaks in excess of 5500 m and the second‐highest peak in Peru, Nevados Yerupaja (6617 m). Bedrock is dominated by folded Mesozoic miogeoclinal rocks unconformably overla…
We have fabricated light-emitting diodes with a transparent doping layer on silicon nanocrystals (nc-Si) embeded in silicon nitride matrix formed by plasma-enhanced chemical vapor deposition. Under forward biased condition, orange electroluminescence (EL) with its peak wavelength at about 600 nm was observed at room t…
We present a combined experimental and theoretical study on copper pyrimidine dinitrate $[\mathrm{C}\mathrm{u}\mathrm{P}\mathrm{M}({\mathrm{N}\mathrm{O}}_{3}{)}_{2}({\mathrm{H}}_{2}\mathrm{O}{)}_{2}{]}_{n}$, a one-dimensional $S=1/2$ antiferromagnet with alternating local symmetry. From the local susceptibility measur…
We develop a multidimensional coupled channel method suitable for studying the interplay of bound state resonance and phonon assisted scattering of inert gas atoms from solid surfaces in one, two and three dimensions. This enables us to get insight into the features that depend on the dimensionality of inelastic reson…
Magnetic and heat capacity measurements have been carried out on the polycrystalline sample of DyNi which crystallizes in the orthorhombic FeB structure (space group Pnma). This compound is ferromagnetic with a Curie temperature of 59 K. Magnetization-field isotherms at low temperatures shows a step-like behavior char…
As shown by Overhauser and others, accurate pair densities for the uniform electron gas may be found by solving a two-electron scattering problem with an effective screened electron-electron repulsion. In this work we explore the extension of this approach to nonuniform systems, and we discuss its potential for densit…
A remarkably strong dependence of magnetoimpedance (MI) on tensile stress has been observed in the microwave frequency range for thin CoMnSiB glass-coated microwires exposed to a special thermal treatment. The MI ratio runs into more than 100% at 0.5-1.5 GHz when the tensile stress of 600 MPa is applied to the wire. I…
Tris-beta-diketonate lanthanide(III) complexes (Ln = Eu, Er, Yb, Tb), of general formula [Ln(acac)3 L(m)], with chelating ligands such as 4,7-disubstituted-1,10-phenanthrolines and 4,4'-disubstituted-2,2'-bipyridines, have been synthesized and fully characterized. The inductive effects of the para-substituents on the…
Rapid synthesis of wurtzite ZnS nanowires and nanoribbons has been achieved by a simple thermal evaporation of ZnS powder onto Si substrate in the presence of Au catalyst. A vapor-liquid-solid process is proposed for the formation of the ZnS nanostructures. The flow rate of the inert carrier Ar gas along with the temp…