Electrical properties of a solid polymeric electrolyte of PVC–ZnO–LiClO4

The ZnO filler has been introduced into a solid polymeric electrolyte of polyvinyl chloride (PVC)–ZnO–LiClO₄, replacing costly organic filler for conductivity improvement. Ionic conductivity of PVC–ZnO–LiClO₄ as a function of ZnO concentration and temperature has been studied. The electrolyte samples were prepared by solution casting technique. The ionic conductivity was measured using impedance spectroscopy technique. It was observed that the conductivity of the electrolyte varies with ZnO concentration and temperature. The temperature dependence on the conductivity of electrolyte was modelled by Arrhenius and Vogel–Tammann–Fulcher equations, respectively. The temperature dependence on the conductivity does not fit in both models. The highest room temperature conductivity of the electrolyte of 3.7 × 10⁻⁷ Scm⁻¹ was obtained at 20% by weight of ZnO and that without ZnO filler was found to be 8.8 × 10⁻¹⁰ Scm⁻¹. The conductivity has been improved by 420 times when the ZnO filler was introduced into the PVC–LiClO₄ electrolyte system. It was also found that the glass transition temperature of the electrolyte PVC–ZnO–LiClO₄ is about the same as PVC–LiClO₄. The increase in conductivity of the electrolyte with the ZnO filler was explained in terms of its surface morphology.     

Comprehensive study of a 4H–SiC MES–MOSFET

In this paper, we studied the enhancement of the breakdown voltage in the 4H–SiC MESFET–MOSFET (MES–MOSFET) structure which we have proposed in our previous work. We compared this structure with Conventional Bulk-MOSFET (CB-MOSFET) and Field plated Conventional Bulk-MOSFET (FCB-MOSFET) structures. The 4H–SiC MES–MOSFET structure consists of two additional schottky buried gates which behave like a Metal on Semiconductor (MES) at the interface of the active region and substrate. The motivation for this structure was to enhance the breakdown voltage by introducing a new technique of utilizing the reduced surface field (RESURF) concept. In our comparison and investigation we used a two-dimensional device simulator. Our simulation results show that the breakdown voltage of the proposed structure is 3.7 and 2.9 times larger than CB-MOSFET and FCB-MOSFET structures, respectively. We also showed that the threshold voltage and the slope of drain current (I_D) as a function of drain–source voltage (V_DS) for all the structures is the same.     

Effect of Hydrogen on Young’s Modulus and Internal Friction of V–4Ti–4Cr Alloy

Physics of the Solid State - We studied Young’s modulus and internal friction of the V–4Ti–4Cr alloy with different hydrogen impurity concentrations in the temperature range of...     

Radiative Characteristics of Xe2Cl* Molecules under High-Energy Electron Pumping of Xe–CCl4 and Ar–Xe–CCl4 Gas Mixtures with a Low CCl4 Content

Optics and Spectroscopy - Spontaneous and stimulated emissions of Xe2Cl* triplex molecules upon excitation of Xe–CCl4 gas mixtures with a low CCl4 content by a pulsed high-energy electron...     

Mechanism of texture and microstructure evolution during warm rolling of Ti–6Al–4V alloy

Ti–6Al–4V (Ti64) plates were subjected to rolling at 600°C and 800°C, respectively, for reductions up to 90% reduction in thickness. The mechanism of texture and microstructure evolution during rolling was studied in the present study. Extension twins of coherent nature were observed in the samples rolled up to 50% of reduction. The deformation was relatively inhomogeneous in the samples rolled at 600°C compared to that at 800°C. Visco-plastic self-consistent (VPSC) simulation showed that relative activity of pyramidal <c+a> slip was higher during rolling at 800°C compared to that at 600°C. The average activity of slip systems per grain was less than five for the samples rolled at 600°C and this might be responsible for the strain heterogeneity in the large grains. Further, twinning activity was found to be limited to a true strain of 0.5, as supported by the microstructural observation. VPSC simulation also showed the presence of contraction twins in the samples which was further supported by X-ray texture measurement. Dominant basal texture was observed in the samples irrespective of the temperature of rolling.     

Strain behavior of the hydrogenated submicrocrystalline Ti–6Al–4V alloy

Comparative studies of the influence of 0.002–0.12 mass % hydrogenation on the structure and phase composition of the submicrocrystalline and coarse-grained Ti–6Al–4 V alloys are performed. The evolution of the strain processes in the hydrogenated alloy is studied for both alloys upon tension at a temperature of 293 K depending on the hydrogen content and alloy state. It is established that the presence of hydrogen in the nanostructured Ti–6Al–4 V alloy in the solid solution leads to a decrease of its yield stress and an increase of its tensile strength and total strain before failure. The possible reasons for the increased duration of the uniform strain stage and the effect of strain hardening of the alloy in the presence of hydrogen in the solid solution are discussed.     

Ultrasonic cavitation erosion of gas nitrided Ti–6Al–4V alloys

Ultrasonic cavitation erosion experiments were performed on Ti–6Al–4V alloys samples in annealed, nitrided and nitrided and subsequently heat treated state. The protective oxide layer formed as a result of annealing and heat treatment after nitriding is eliminated after less than 30 min cavitation time, while the nitride layer lasts up to 90 min cavitation time. Once the protective layer is removed, the cavitation process develops by grain boundary erosion, leading to the expulsion of grains from the surface. The gas nitrided Ti–6Al–4V alloy, forming a Ti_xN surface layer, proved to be a better solution to improve the cavitation erosion resistance, compared to the annealed and nitrided and heat treated state, respectively. The analysis of the mean depth of erosion rate at 165 min cavitation time showed an improvement of the cavitation erosion resistance of the nitrided samples of up to 77% higher compared to the one of the annealed samples.     

Structure of connections of single-walled carbon nanotubes with the use of the combined 5–7 and 4–8 topological defects

The structures of zigzag-zigzag, armchair-zigzag, zigzag-chiral, armchair-armchair, armchair-chiral, and chiral-chiral pair connections produced by single-walled carbon nanotubes 1.5–5.0 diameter with the use of the combined 5–7 and 4–8 topological defects have been calculated by molecular mechanics methods. It has been established that the use of the combined 5–7 topological defect makes it possible to produce connections between pairs of single-walled carbon nanotubes with any conductivities, chiralities, and diameters, whereas the use of the combined 4–8 topological defect provides a means for forming connections between nanotubes only with the same type of conductivity. The angles between the axes of nanotubes connected by the combined 5–7 and 4–8 topological defects lie in the ranges 145°–180° and 112°–178°, respectively. It has been revealed that there are correlations between structural parameters of the connections and the relative arrangement of the simple topological defects in the combined topological defects.     

Cu2ZnSnSe4 films by selenization of Sn–Zn–Cu sequential films

This paper deals with the formation of Cu₂ZnSnSe₄ (CZTS) in the process of selenization of metal precursor layers in elemental selenium vapour. Metallic precursors were sequentially evaported from Sn, Zn and Cu sources. Precursor Sn–Zn–Cu films have a “mesa-like” structure and consist mainly of Cu₅Zn₈ and Cu₆Sn₅ phases. It was confirmed that the formation of different binary copper selenides is the dominating process of selenization in elemental Se vapour at temperatures up to 300 °C. The formation of kesterite CZTS films begins at 300 °C and dominates at higher temperatures, always resulting in multiphase films that consist of high-quality Cu₂ZnSnSe₄ crystals and of a separate phase of ZnSe.     

Structural study of NiXMg1–XFe2O4 ferrites

The ferrite system Ni _x Mg_1-x Fe₂O₄ with 0≤x≤1 was prepared using the usual ceramic technique. The prepared samples were studied by X-ray diffraction and IR spectroscopy. X-ray diffraction analysis proved that all the samples were single-phase with the cubic spinel structure. The lattice constant, radius of the tetrahedral ion, unshared octahedral edge, tetrahedral bond and tetrahedral edge decrease while the bulk and theoretical densities, radius of octahedral ion, octahedral bond and shared octahedral edge increase as nickel ion substitution increases. The positions and intensities of the four bands of IR absorption spectra characterizing ferrites are composition dependent.     

Spectral structure of barium–phosphate–silicate phosphor Ba10(PO4)4(SiO4)2:EuM+

The new apatite–silicate phosphor doped with Eu ions in Ba₁₀(PO₄)₄(SiO₄)₂ matrix was synthesized through solid-state reaction. It was found that the as-synthesized phosphor displayed apparent mixture of band and line emission peaks giving rise to pseudo white light. The narrow emission bands peaking at 410 nm can be assigned to the 4f⁶5d→4f⁷(⁸S_7/2) transition of Eu²⁺ ions, and the other band at 507 nm is ascribed to anomalous fluorescent emission. One group of line emission peaking at 595 nm and 613 m were due to the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transition of Eu³⁺ ions. The occurrence of photostimulated luminescence and discrete emission lines in violet (410 nm), green (507 nm) and red (595 nm and 613 nm) colors indicate that this material has potential application in fields of white-light-emitting.     

Fabrication and characterization of the normally-off N-channel lateral 4H–SiC metal–oxide–semiconductor field-effect transistors

In this paper, the normally-off N-channel lateral 4H–Si C metal–oxide–semiconductor field-effect transistors(MOSFFETs) have been fabricated and characterized. A sandwich-(nitridation–oxidation–nitridation) type process was used to grow the gate dielectric film to obtain high channel mobility. The interface properties of 4H–Si C/SiO_2 were examined by the measurement of HF I–V, G–V, and C–V over a range of frequencies. The ideal C–V curve with little hysteresis and the frequency dispersion were observed. As a result, the interface state density near the conduction band edge of 4H–Si C was reduced to 2 × 10~(11) e V~(-1)·cm~(-2), the breakdown field of the grown oxides was about 9.8 MV/cm, the median peak fieldeffect mobility is about 32.5 cm~2·V~(-1)·s~(-1), and the maximum peak field-effect mobility of 38 cm~2·V~(-1)·s~(-1) was achieved in fabricated lateral 4H–Si C MOSFFETs.     

Synthesis,Structure, and Thermal Properties of the YVO4–BiVO4 Oxides

Physics of the Solid State - The Y0.4Bi0.6VO4 and Y0.6Bi0.4VO4 solid solutions two-phase at xBi = 0.95, 0.90, and 0.80 have been formed by the solid-phase synthesis from the initial Y2O3, Bi2O3,...     

Contributions of different strengthening mechanisms to the shear strength of an extruded Mg–4Zn–0.5Ca alloy

The shear deformation behaviour of an extruded Mg–4Zn–0.5Ca alloy was studied using shear punch testing at room temperature. The extrusion process effectively refined the microstructure, leading to a grain size of 4.6 ± 1.4 μm. Contributions of different strengthening mechanisms to the room temperature shear yield stress, and overall flow stress of the material, were calculated. These mechanisms include dislocation strengthening, grain boundary strengthening, solid solution hardening and strengthening resulting from second-phase particles. Grain boundary strengthening and solid solution hardening made significant contributions to the overall strength of the material, while the contributions of second-phase particles and dislocations were trivial. The observed differences between calculated and experimental strength values were discussed based on the textural softening of the material.     

Electronic Structure of Immunoactive Molecules of 8–Azagona–12,17–Dione

Using the semiempirical method of partial neglect of differential overlap (PNDO), we have calculated the wave functions, energies, orbital configurations of electronic states, oscillator strengths of transitions, electronic density distributions, and dipole moments for the molecule of biologically active 8–azagona–12,17–dione, containing a conformationally rigid –acyl––aminovinylcarbonyl fragment. It has been established that as to their orbital nature the excited lower and higher singlet electronic states of this molecule are of the n^*– and ^* type respectively. The results of the theoretical analysis are in good qualitative agreement with the spectral data on absorption and luminescence. The calculations of the intermolecular interaction of the compound under consideration with a medium show that the molecular systems under consideration can possess a dynamic multicenter structure.     

The origin of the Ca–Ti–Cr–Fe–Ni isotopic anomalies in the inclusion EK-1-4-1 of the Allende meteorite

The origin of the correlated Ca–Ti–Cr–Fe–Ni isotopic anomalies in the Ca–Al-rich inclusion of the EK-1-4-1 of the Allende is a longstanding puzzle. The search for a stellar environment which could explain the enrichment of neutron-rich stable Ca–⋯–Ni isotopes in a self-consistent way requires nuclear physics data far from stability. Recent experimental data have been obtained in the region of the shell closures N=28 and N=40, where the possible progenitors of these nuclei are found. Astrophysical network calculations have been updated by including the new β-decay properties and microscopic predictions of neutron-capture cross sections. Interplay between nuclear structure far from stability and the observed isotopic anomalies is especially evident for the high entropy (S≃150) scenario which would characterize the neutrino-driven wind in a type II supernova. To cite this article: O. Sorlin et al., C. R. Physique 4 (2003).     

Variational Calculation of 4He Tetramer Ground and Excited States Using Realistic 4He–4He Potentials

We calculated binding energies and wave functions of the ⁴He tetramer ground and excited states employing various realistic ⁴He?⁴He potentials which includes the currently most accurate one with the adiabatic, relativistic, QED and residual retardation corrections. We used our Gaussian expansion method (GEM) for ab initio variational calculations of few-body systems. We found that precisely the same shape of the short-range correlation (r _ij < 4Å) in the dimer appear in the ground and excited states of trimer and tetramer. The four kinds of the binding energies of the trimer and tetramer ground and excited states, ${B_3^{(0)}, B_3^{(1)}, B_4^{(0)}}$ and ${B_4^{(1)}}$ , for the different potentials exhibit perfect linear correlations over the range of binding energies relevant for ⁴He atoms; namely, six types of the generalized atomic Tjon lines were observed.     

Laser surface modification of Al–4Cu–1Mg alloy for enhanced thermal conductivity

The feasibility of enhancing thermal conductivity of Al–4Cu–1Mg alloy by depositing 80Cu–20Mo coating using high-power lasers has been examined. Coatings of 667±2.5 μm thickness were formed with metallurgically sound interface. Results showed an 86% increase in the thermal conductivity of Al–4Cu–1Mg alloy due to laser-deposited 80Cu–20Mo alloy coating. This coating approach can potentially be used on low coefficient of thermal expansion metal matrix composites to enhance their thermal conductivity in electronic devices.     

Luminescence Characterisation of the Reaction System Histidine–KBrO3–Tb(III)–H2SO4

Chemiluminescence of the system containing Tb(III) ions, histidine and bromate ions in acid solution was studied. The kinetic curves and CL emission spectra of the system were discussed. The emission spectrum of the histidine–Tb(III)–KBrO₃–H₂SO₄ system revealed two emission maxima at ∼490 and 550 nm, characteristic of Tb(III) ions. Values of lifetimes of the Eu(III) excited states in Eu(III)–histidine system have shown that the histidine formed ML and ML₂ complexes in neutral solution and did not make them in acidic environment. On the basis of the results, a possible mechanism of reaction system: histidine–Tb(III)–KBrO₃–H₂SO₄ is presented.