Materials Literature
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We have explored the effects of the Li intercalation on the electronic and magnetic properties of transition-metal (TM) doped anatase TiO$_2$. By Li intercalation, Mn-doped TiO$_2$ exhibits the insulator to metal transition. On the other hand, Li-intercalated Fe-doped TiO$_2$ has the insulating ground state for low co…
For the low molecular weight fragile liquid diglycidyl ether of bisphenol A we report, based on Brillouin and dielectric spectroscopy, on a thermal glass transition where the relaxation time of the alpha process does not go to infinity. Instead, the structural alpha relaxation disappears spontaneously at the transitio…
The dielectric fluctuations in the uniaxial nematic phase of a bent-core liquid crystal have been studied by dynamic light scattering. Polarization selection of the scattering cross-section reveals one mode due to ordinary director fluctuations and, in the lower part of the nematic phase, a second mode attributable to…
We investigate the sensitivity of x-ray absorption spectroscopy to cubic-hexagonal polytypism in which nearest-neighbor positions are virtually unchanged. Experimental spectra and multiple-scattering calculations are reported at the major absorption edges in the zinc-blende and wurtzite modifications of ZnS. We demons…
Composite materials have grown rapidly both in their applications and their economic importance, and they will no doubt continue to do so. With this growth has come increased attention in engineering curricula, but most coursework tends to focus on laminate theory and the analysis of composites, not on the practical d…
The heat capacity of solid Kr-CH4 solutions with 30 and 60 mol.% CH4 has been studied at 0.8-20 K. The contribution of the rotational subsystem Crot to the heat capacity of the solutions is separated. The results obtained in this study and Ref. [4] were used to estimate the difference between the lowest-level energies…
We review investigations of the electron-phonon interaction (EPI) in metal diborides MeB_2 (Me=Zr, Nb, Ta, Mg) by point-contact (PC) spectroscopy. For transition metal compounds the PC EPI functions were recovered and EPI parameter $λ\lesssim 0.1$ were estimated. The data are consistent with the measured surface phono…
It has been established in nineteen seventies that in nonequilibrium case the pair collisions generate non-zero two-particle correlations which are non-diagonal in momentum space and give the essential contribution to the current fluctuations of hot electrons. It is shown here that this correlations give also a contri…
Effects of processing parameters and thickness on the properties of spin-on SrBi/sub 2/Ta/sub 2/O/sub 7/ (SET) films were investigated. Film crystallinity was improved with heat treatment but surface roughness also increased significantly above 400/spl deg/C. Capacitor polarization was found to be a function of electr…
High density polyethylene (HDPE) and low density polyethylene (LDPE) are widely used as dielectrics and insulating materials. In this paper, the influence of heat treatment during and after corona charging on charge storage stability and the transportation of detrapping charges in the bulk of HDPE and LDPE were invest…
Applicability of polyethylene polymerized using a metallocene catalyst to an insulation material for DC power cables has been investigated. The accumulation properties of space charge in a range from room temperature to 90/spl deg/C was examined using the pulse electroacoustic method. The result indicated that hetero-…
Abstract For Abstract see ChemInform Abstract in Full Text.
Ageing due to multifactor stresses of the surface of organic materials has to be divided into two different stages named "early" and "late" stage of ageing. While standardized tests such as the inclined plane test or the rotating wheel dip test aim at verifying only the performance of insulating materials in the late…
Partial discharges (PD) are an indication of weak spots in the insulation of DC high voltage equipment. For AC equipment, classification of the type of defect can be achieved if statistical tools are used on the PD phase distributions. In this paper, the authors propose the use of a similar technique for classificatio…
Extruded crosslinked polyethylene (XLPE) insulation is widely used in high-voltage cables since it presents such attractive features as excellent dielectric properties and good thermomechanical behavior. However, its performance is affected by long-term degradation when it is subjected to the various thermal, mechanic…
Experimental results of accelerated aging tests conducted on two types of high voltage polymeric outdoor insulators are presented. The investigated housing polymers were ethylene propylene diene monomer (EPDM) and silicone rubber (SR). The polymer performance under environmental stresses and electrical stresses were s…
The heat capacity of SrFeO3−δ; δ = 0.50, 0.25 and 0.15 has been determined for 10 < T/K < ≈ 800 K by adiabatic calorimetry. The total heat capacity has been analysed and the entropy of the magnetic and structural order–disorder transitions derived. The excess heat capacity of SrFeO2.50 relative to the mixture of the b…
Sol-gel derived ZnO thin films were prepared on platinized Si wafers and fired to temperatures ranging from 550C to 700C. Multiple spincoating was performed with an intermediate firing at 400C between coatings to obtain films up to 6000 A thick. Top Pt electrodes were sputtered to form monolithic capacitors. Dielectri…
Abstract For Abstract see ChemInform Abstract in Full Text.
Computer aided partial discharge detection, recognition and classification at AC voltage has become common practice in recent years. Characteristic discharge phase distributions have been found, thus providing the possibility to recognise and assess possible defects in HV apparatus. For diagnostic purposes, fingerprin…