Materials Literature
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Light illumination produces major, interesting changes of the electrical properties of oxygen deficient ${\mathrm{La}}_{2/3}{\mathrm{Sr}}_{1/3}{\mathrm{MnO}}_{3\ensuremath{-}\ensuremath{\delta}}$ thin films. At small oxygen deficiency, the classical insulator-metal $(I\ensuremath{-}M)$ transition at a temperature ${T}…
Piezoelectric and dielectric measurements were performed on different batches of polarized NaNbO 3 ceramics. It has been established that, as a result of polarization, in these ceramics there appears a metastable ferroelectric phase existing for a long time. The presence of this phase manifests itself as a piezoelectr…
We report the preparation and solid-state characterization of the perchlorophenalenyl radical (1). The radical is initially obtained as a yellow-green solid by reduction of the perchlorophenalenium salt (12(+)). This solid sublimes in a sealed tube to give black shiny hexagonal crystals of the perchlorophenalenyl radi…
An efficient method is described to handle mesh indexes in multidimensional problems like numerical integration of partial differential equations, lattice model simulations, and determination of atomic neighbor lists. By creating an extended mesh, beyond the periodic unit cell, the stride in memory between equivalent…
The performance of basis sets made of numerical atomic orbitals is explored in density-functional calculations of solids and molecules. With the aim of optimizing basis quality while maintaining strict localization of the orbitals, as needed for linear-scaling calculations, several schemes have been tried. The best pe…
We study the influence of surface roughness on the adhesion of elastic solids. Most real surfaces have roughness on many different length scales, and this fact is taken into account in our analysis. We consider in detail the case when the surface roughness can be described as a self affine fractal, and show that when…
We describe a method for calculating the exchange and correlation (XC) contributions to the total energy, effective potential, and stress tensor in the generalized gradient approximation. We avoid using the analytical expressions for the functional derivatives of E_xc*rho, which depend on discontinuous second-order de…
Homogeneous films of Au@SiO 2 particles have been deposited on glass as a prototype 3D “artificial solid” using the LBL method. The film thickness is controlled by the number of dipping cycles and is measured by AFM. Each cycle results in approximately one monolayer of particles being deposited. The particle films are…
Carbon nanoparticles were prepared from H2 and CH4 at various temperatures. The carbon nanoparticles were well graphitized, and the degree of graphitization increased with increasing growth temperature. Field-emission measurements showed that the carbon nanoparticles were excellent electron field emitters, comparable…
We explored the feasibility of employing strontium titanate (SrTiO3) as semiconducting material in field-effect metal–insulator–semiconductor epitaxial heterostructures. This idea was suggested by the observation of a dramatic effect of the oxygen deficiency on SrTiO3−δ transport properties, which brings about metalli…
This letter reports on a process to prepare nanostructured PbTiO3 (PT) at room temperature with photoluminescence (PL) emission in the visible range. This process is based on the high-energy mechanical milling of ultrafine PbTiO3 powder. The results suggest that high-energy mechanical milling modifies the particle’s s…
Modeling the conductive channel as a series of ferromagnetic (FM) domain with resistivity of ${\ensuremath{\rho}}_{\mathrm{FM}}$ and paramagnetic (PM) region with resistivity of ${\ensuremath{\rho}}_{\mathrm{PM}},$ we propose a phenomenological equation for resistivity as $\ensuremath{\rho}=[1\ensuremath{-}f(T,H)]{\en…
The spontaneous generation of voltage has been observed during the first-order magnetic-Martensitic phase transition process in ${\mathrm{Gd}}_{5}{(\mathrm{S}\mathrm{i}}_{x}{\mathrm{Ge}}_{4\ensuremath{-}x})$ alloys regardless of whether the transformation is triggered by temperature or magnetic field. Based on various…
In a diffusion-controlled interaction, the Kirkendall plane, as marked by inert particles placed at the original contact surface of a reaction couple, need not be unique. Multiple planes can develop, and sometimes the Kirkendall plane does not exist at all. A phenomenological approach is introduced to rationalize the…
Nearest- and higher-neighbor distances as well as bond length distributions (static and thermal) of the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ $(0<~x<~1)$ semiconductor alloys have been obtained from high-real-space resolution atomic pair distribution functions. Using this structural info…
Aligned carbon nanotubes (CNTs) with diameters of 50–100 nm, synthesized by plasma-assisted hot filament chemical vapor deposition, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. Quadruple mass spectroscopy and thermogravimetric analysis show a hydrogen storage capacity o…
Giant dielectric permittivity was observed in La-modified PbTiO (3) (PLT) with A-site vacancy. The observed values of PLT with A-site vacancy are 1 order of magnitude larger than those of relaxor ferroelectrics. The giant relative dielectric permittivity, coupled with a low dielectric loss (tandelta approximately 0.03…
We study optically single self-assembled quantum dots embedded within the wide quantum well of a mixed type quantum structure. We compare the steady state and pulsed photoluminescence spectra of these dots to those of previously studied "regular" dots. We unambiguously identify experimentally emission from various dis…
We report first-principles all-electron density-functional-based studies of the electronic structure, magnetic ordering, and anisotropy for the V15 molecular magnet. From these calculations, we determine a Heisenberg Hamiltonian with five antiferromagnetic and one ferromagnetic exchange couplings. We perform direct di…
We use ab initio total-energy calculations to predict the existence of polarons in semiconducting carbon nanotubes (CNTs). We find that the CNTs' band edge energies vary linearly and the elastic energy increases quadratically with both radial and with axial distortions, leading to the spontaneous formation of polarons…