Materials Literature
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In this article we report the development of Fe modified BaTiO3 using sol-gel technique and present results of structural and dielectric studies to establish its suitability for pyroelectric sensor applications. Fine powders of Fe modified BaTiO3 were prepared by sol-gel process using barium acetate, iron isopropoxide…
The hard magnetic properties of nitrided melt-spun R(Fe,M)12 (R=Pr and Nd, M=V and Mo) ribbons have been investigated. Hard magnetic powders were prepared by vacuum annealing of ground ribbons in the temperature range from 700 to 950 °C and subsequent nitrogenation. For NdFe10.5Mo1.5Nx and PrFe10.5Mo1.5Nx powders, coe…
Time-resolved measurements of photoluminescence were carried out on a hydrogenated amorphous silicon nitride film prepared by low-pressure chemical vapor deposition. When excited with 5.0-eV photons, photoluminescence occurs over a broad spectrum ranging from 1.8 to 3.6 eV. The peak energy of this photoluminescence va…
Thin films of Bi2VO5.5 have been prepared epitaxially using a pulsed-laser deposition method on a Si(100) substrate using TiN as a buffer layer and SrTiO3 as a seed layer. The films have smooth surface morphology with atomically flat terraces and steps of 4 Å in height. The ferroelectric characterization shows a spont…
We present a characterization of lateral silicon pn junction arrays fabricated on a Si(001) surface using a synchrotron-based scanning photoelectron microscope (SPEM). The Si 2p images show energy dependent contrast which varies continuously across the space charge region between regions of different doping. Combined…
We propose a transition state for oxygen in silica. This state is produced by the insertion of an oxygen molecule into the Si--O--Si bond, i.e., it consists of producing a Si--O--O--O--Si bond. This state allows molecular oxygen diffusion in silica without breaking the molecular ${\mathrm{O}}_{2}$ bond and it is energ…
By solving a set of differential rate equations the precipitation of AgCl clusters in the glass system 30Na2O–70B2O3/AgCl has been modeled. Using a parallel algorithm on a CRAY T3E it was possible to investigate the process of homogeneous nucleation and growth, which starts after an initial quench of the glass melt in…
The defect formation in epitaxial NaCl films (up to 5.6 nm thick) during low-energy (50--1500 eV) electron bombardment has been studied by a combination of low-energy electron diffraction and energy loss spectroscopy. At temperatures below 200 K two types of color center are generated at the surface, showing distinct…
We propose a phase diagram of quasi-low-dimensional type II superconductors in parallel magnetic fields, when antiferromagnetic fluctuations contribute to the pairing interactions. We point out that pairing interactions mediated by antiferromagnetic fluctuations necessarily include both singlet channels and triplet ch…
Organometallic polycondensation gave zinc porphyrin (Por) polymers (e.g., (−Ar−Por-Ar−) n and (−C⋮C−Por-C⋮C−Ar−) n; Ar = arylene) having arylene or aryleneethynylene groups between the zinc porphyrin units. Polymers having long alkyl substituent(s) in the Ar unit were soluble in THF and chloroform, and gave M n and M…
Laser ablation deposition of highly oriented yttria stabilized zirconia (YSZ) films is important for various technological applications and depends critically on the selection of background environment, with low pressure oxygen being the most common choice. Here, the spatial-temporal distribution of YSZ plume chemistr…
We have experimentally observed that the optical absorption spectra of single-walled carbon nanotube (SWCNT) films change drastically and reversibly by pressure up to 4.1 GPa. The main absorption feature at 0.68 eV attributed to the interband optical transition in semiconducting nanotubes [chiral $(n,m)$ and zigzag $(…
In this article, we will report the low temperature Raman studies of Li0.12Na0.88NbO3 ceramics at the ferroelectric–ferroelectric phase transitions. The spectral pattern indicates the phase transition occurs at 200 K in the cooling process and at 280 K on heating. The observed spectra are discussed as they relate to t…
The aim of this work is to present an electrical study of the aging of conducting polyaniline–polystyrene (PANl–PSt) blends. Results concerning time dependence of the electrical conductivity of some samples artificially aged at different temperatures are presented. It is shown that the electrical conductivity decrease…
A force field for phosphoric acid is developed, on the basis of the reproduction of the experimental crystal structure by molecular dynamics (MD) simulations. The fit between calculated and experimental unit cell parameters, atomic positions, thermal motions, and hydrogen bond distances is satisfactory. Subsequently,…
Quasiparticle energies of AlN, GaN, ZnO, ZnS and ZnSe in the wurtzite structure have been calculated by the GW approximation with a full random phase approximation dielectric matrix instead of using plasmon pole approximation. The linear muffin tin orbital basis was used for this work and the d orbitals of the Zn and…
A phosphate glass embedded with PbSe semiconductor quantum dots (QDs) has been synthesized and investigated. Optical absorption spectra of PbSe spherical QDs have been studied both theoretically and experimentally. Theoretical analysis of the energy spectra and optical transitions has been carried out in the framework…
We study theoretically the collective orbital excitation called the orbital wave in the orbital ordered manganites. The dispersion relation of the orbital wave is strongly correlated with the static spin structure through the coupling between spin and orbital degrees of freedom. As a probe to detect the dispersion rel…
Development of long-range order in relaxor ferroelectrics [Pb(Mg 1/3 Nb 2/3 )O 3 ] 1- x -[PbTiO 3 ] x (PMN/ x PT) and Pb(Zn 1/3 Nb 2/3 )O 3 (PZN) has been investigated by neutron powder diffraction and birefringence along with transmission-electron and optical microscopies. The Rietveld analysis of PZN revealed that t…
We demonstrate the first three-dimensional simulations of bicontinuous spinodal decomposition of incompressible binary fluid mixtures in a confined geometry. We find that after an initial transient the thickness of a wetting layer L grows with time t as L ∼ t 1/3 by a diffusion process and later as L ∼ t by a hydrodyn…