Density functional theory calculations have been performed on stoichiometric and intrinsically defective p-type transparent conducting oxide SrCu2O2, using GGA corrected for on-site Coulombic interactions (GGA + U). Analysis of the absorption spectrum of SrCu2O2 indicates that the fundamental direct band gap could be as much as 0.5 eV smaller than the optical band gap. Our results indicate that...

We report the synthesis of carbon nanotube/TiC hybrid fibers using a polymer-assisted chemical solution approach. Ti metal ions are bound to aqueous polyethyleneimine (PEI) to form precursor solution. Amphiphilic PEI with Ti easily permeates the CNT fibers. Upon annealing in a controlled atmosphere, a homogeneous TiC network is formed in the CNT fibers. The obtained CNT/TiC hybrid fibers show p...

A numerical study of the energy relaxation and conductivity of the Coulomb glass is presented. The role of many-electron transitions is studied by two complementary methods: a kinetic Monte Carlo algorithm and a master equation in configuration space. A calculation of the transition rate for two-electron transitions is presented, and the proper extension of this to multielectron transitions is ...

Li2O·0.25Fe2O3·0.25NiO·1.5SiO2 glass was prepared with and without 5 wt % sulfur (S) while melting the mixture of the starting materials at 1350 C for 1 h in air. A part of the as-prepared glass was heat treated for 1 h near its crystallization temperature (Tc) as determined from differential thermal analysis. Each glass was also investigated by means of Mössbauer spectroscopy, X-ray diffracti...

The conductivity of high-resistivity polymer films is dependent on the magnitude of applied electric field, repeated electric field exposure, and sample temperature. A traditional constant voltage method was used, maintained under vacuum to more closely resemble the space environment. Both the strength of the applied voltage and the thickness of low-density polyethylene (LDPE) samples were vari...

The dielectric properties and AC conductivity of pure and doped PVA samples with different concentrations of CuCl2 and Thiourea are investigated in the frequency range from 0.2 Hz to 100 kHz within a temperature range from room temperature to 433 K. It is observed that the dielectric constant decreases with an increase of frequency for all samples. The behaviour of the dielectric loss (ε'') as ...

The variable range hopping theory has been widely used these last years to explain the electric conduction process in some biological systems as DNA. However, the experimental measurements on such systems reveal that the density of states varies strongly near Fermi level. This observation suggests that the theoretical concept of "constant density of states" near Fermi level is certainly insuffi...

We investigate the shielding effectiveness and complex conductivity of single-walled carbon nanotubes (SWNT) distributed in a polyvinyl alcohol (PVA) matrix in the THz frequency range. SWNTs are dispersed in PVA matrices with varying SWNT content (keeping the thickness of SWNT/PVA film constant) using a slow-drying method, and terahertz time-domain spectroscopy (THz-TDS) is performed at room te...

The f-sum rule is introduced and its applications to electronic and vibrational modes are discussed. A related integral over the intra-band part of σ(ω) which is also valid for correlated electrons, becomes just the kinetic energy if the only hopping os between nearest-neighbor sites. A summary is given of additional sum-rule expressions for the optical conductivity and the dielectric function,...