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حرية الوصول المقاله
1 - Relativistic dynamics of electrons around impurities in high-density plasmas
Said Douis Mohammed Tayeb MeftahAbstractIn this work, we focus our attention on the dynamic properties of relativistic electrons moving around an impurity in a plasma. This led us, in the first place, to compute the effective plasma potential (EPP) in which the electrons move. The EPP is built up as a أکثرAbstractIn this work, we focus our attention on the dynamic properties of relativistic electrons moving around an impurity in a plasma. This led us, in the first place, to compute the effective plasma potential (EPP) in which the electrons move. The EPP is built up as a sum of three contributions. These include the potential created by the impurity, the potential due to the ions assumed to form a uniform background of positive electric charges and the potential due to all the electrons. It turns out that the last potential depends on an integral of a function of the EPP in question. This then leads to a nonlinear integral equation where the EPP is the main quantity to compute. Thanks to the EPP, we derive the electron trajectories and compute their total electric field (microfield) at the impurity. According to different plasma conditions, two dynamical properties are then calculated: the time auto-correlation function of this microfield and the dielectric constant. These properties are calculated for both the relativistic case and non-relativistic (classical) case. The comparison between the relativistic and the classical results are also done for the different plasma conditions. تفاصيل المقالة -
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2 - Temperature dependence dielectric behavior of Ge-doped lead scandium tantalate single crystals
Chandra Kumar Dixit Anil Kumar SrivastavaAbstractThe doping of Pb2SeTaO6 with Ge ferroelectrics was produced by a high-temperature solution method. We measure dielectric constant, dielectric loss and conductivity in the temperature range −30°C to 200°C and frequency range 1 to 100 KHz. The value of dielectric أکثرAbstractThe doping of Pb2SeTaO6 with Ge ferroelectrics was produced by a high-temperature solution method. We measure dielectric constant, dielectric loss and conductivity in the temperature range −30°C to 200°C and frequency range 1 to 100 KHz. The value of dielectric constant of the Pb2SeTaO6 (PST) crystal remained the same after thermal annealing whereas they decreased after Ge doping in the phase transition temperature range of the PST single crystal. All samples were investigated for conductivity with increasing temperature. تفاصيل المقالة -
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3 - Comparative study of behavior of electrical conductivity in KI‒Al2O3 and KI‒TiO2 heterostructure composites
Suhail Iqbal Wani Nazli Zeeshan RafiuddinAbstractThe present work reports development of binary KI–Al2O3 and KI–TiO2-based nanocomposites using simple solid-state reaction method and is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and impedance spect أکثرAbstractThe present work reports development of binary KI–Al2O3 and KI–TiO2-based nanocomposites using simple solid-state reaction method and is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and impedance spectroscopy. The results show the effect of heterogeneously doped Al2O3 and TiO2 on the ionic conductivity of pure KI which is moderately conductive. The results supported the composite development in which the interface layer portrays a significant part in governing the bulk properties of the compound. Improvement in electrical conductivity is seen in the incorporation of Al2O3 and TiO2 dispersoid into the matrix of KI. With temperature, electrical conductivity increased and the activation energies were found to be decreasing. The activation energies for KI–Al2O3 and KI–TiO2 systems were 0.22 eV and 0.21 eV, respectively, in the temperature range 20‒400 °C. Dielectric constant increases with the increase in temperature in the entire temperature range studied attributed to the phenomenon of distortion of electric charges. تفاصيل المقالة -
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4 - Theoretical Investigation of Solvent Effects on The Structural Changes of I - Pentadeeanoyl - 2 - Docosahexaenoyl - Sn - Glycerol -3 -Phosphoeholin
N. Khodayari B. Honarparvar M. Monajjemi K. ParivarTheoretically predictionq of the solvent effects of I - pentadecanoyl - 2 -docosahexaennyl - Sn - glycerol3 - phosphocholin have been studied using 'Jamey-lock quantiun chemical approximation and STD - 30basis set within the Onsager Self-Consistent Reaction field (SCRS' أکثرTheoretically predictionq of the solvent effects of I - pentadecanoyl - 2 -docosahexaennyl - Sn - glycerol3 - phosphocholin have been studied using 'Jamey-lock quantiun chemical approximation and STD - 30basis set within the Onsager Self-Consistent Reaction field (SCRS') model All optimized conformers of I -pentadecanoyl - 2 -docosahexaenoyI - Sn - glycerol 3 - phosphocholin as well as their total relativeenergies in terms of the most stable conformer in as phase and different solvent media such as water.ethanol. methanol and IMISO have been calculated. According to the obtained resulLz the I - pentadecanoyl- 2 - docosahexaeneyl - Sn - glycerol - 3 - phosphocholin configuration has the most neeative energyvalues and then has been found to be the most stable conformer. In this aspect the gaph of relative energyvalues versus dielectric. constants (c) as well as Ln (I /c) of employed solvents has been plotted and theobserved trend has been analyzed.For further investigation, the effect of solvent's polarity on the dipole moments of 1-pentadecanoyl - 2 -docosahexaenoyl - Sn - glycerol - 3 - phosphocholin in various solvent media have been reported andcompared with the gas phase. We would like to note that the dipole moment variations revealed that thevalues or the computed dipole moment seems to he solvent - dependent because this property is closelyrelated to the en viromnental effects the greatest dipole moment brings more stability which is underinfluence of solvation تفاصيل المقالة -
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5 - Thermodynamics of the solubility of potassium nitrate in the mixed solvent, Ethanol+Water, and the related Ion-association
M. Aghaie F. Ghaemi Amiri M. GiahiUsing the evaporating method, the solubility of potassium Nitrate was determined in various mixtures containing Water and Ethanol at 25°C. The results show that the solubility of KNo3 decreases with increasing the mass percent of Ethanol in the mixtures. This trend أکثرUsing the evaporating method, the solubility of potassium Nitrate was determined in various mixtures containing Water and Ethanol at 25°C. The results show that the solubility of KNo3 decreases with increasing the mass percent of Ethanol in the mixtures. This trend is along with decreasing the dielectric constant of Water+Ethanol mixtures. Moreover, it can be concluded that the totqal solubility of KNO3 may be regarded as the sum of two contributions; one referring to the free ions in the solution and the other to K+NO3-ion-pairs which are formed in the saturated solution. Estimating the formation constant, KAm for the reaction K+(soln) + NO3-(soln) AK+NO3- (ion-pair) , upon Bjerrum or fuoss models, then it is quite easy to evaluate the contributions of free ions and K+NO3-(ion-pair) to the total solubility. تفاصيل المقالة -
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6 - The effect of dielectric constant and ionic strength on the solubility of lithium carbonate at 25.0 °C in thermodynamic view
M. Aghaie S. Ghafoorian B. Sh. Broojeni H. AghaieUsing the Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubilitiesof Li2CO3 were determined in various mixed- solvent "water + ethanol" with various mass percentof ethanol, and in the presence of NaNO3 in various molarities at 25.0°C . Th أکثرUsing the Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubilitiesof Li2CO3 were determined in various mixed- solvent "water + ethanol" with various mass percentof ethanol, and in the presence of NaNO3 in various molarities at 25.0°C . The results wereinterpreted in terms of mean ionic activity coefficient and ion association phenomenon. تفاصيل المقالة -
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7 - The investigation of ionic association in the CdF2 solution with the mixed solvent (water +ethanol +propanol) at 25°C
M. Aghaie T. JaliliUsing the mixed solvents, (water +ethanol + propanol), the solubility of CdF2 was determined byevaporating method at 25° C. The results showed that the sollbility, s, of CdF2 decreases bydecreasing the dielectric constant of the mixed solvent .Once the solubility of أکثرUsing the mixed solvents, (water +ethanol + propanol), the solubility of CdF2 was determined byevaporating method at 25° C. The results showed that the sollbility, s, of CdF2 decreases bydecreasing the dielectric constant of the mixed solvent .Once the solubility of CdF2 was determined,the concentration solubility product, Ksp(c)=4s3, was calculated .Furthermore ,by estimating the meanactivity coefficient, f± , of CdF2 in the solution upon the extended Debye-Hückel theory, the modelsolubility Product constant of the salt, Ksp(m)=4s3 f±3 was calculated .On the other hand we concludedthe equilibrium constant of ion pair formation , KIP, on the basis of Fuoss contact ion pair model andwe obtained the value of ion pair concentration in the mixed solvents, (water 85% +ethanol l5% +propanol 10%). The value of thermodynamic solubility product constant, Ksp(th), of CdF2 in the mixedsolvent was evaluated at zero ionic strength upon the extrapolation method and the value of ion pairconcentration was calculated in the considered solution and compared by fuoss model. تفاصيل المقالة -
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8 - Effect of morphology and nonbounded interface on dielectric properties of plasma sprayed BaTiO3 Coating
Amirhossein Pakseresht Mohamadreza Rahimipour Mohamadreza Vaezi Mehdi SalehiIn this research, BaTiO3 thick deposit has been successfully sprayed by air plasma spray. The microstructure and dielectric properties of thick films were investigated by secondary electron microscopy (SEM) and LCR meter respectively. XRD measurement was carried out on أکثرIn this research, BaTiO3 thick deposit has been successfully sprayed by air plasma spray. The microstructure and dielectric properties of thick films were investigated by secondary electron microscopy (SEM) and LCR meter respectively. XRD measurement was carried out on plasma sprayed BaTiO3. The results illustrate differences in the crystal structure between plasma sprayed coatings and feed stock powders. The as deposited films were mainly crystalline with small amount of an amorphous second phase. The amount of crystalline to amorphous phases was found to be critically dependent upon the degree of melting of feed stock powders. The as-deposited BaTiO3 films had maximum dielectric constant as high as 85 at room temperature. Upon annealing in air at 1050 oC, the dielectric constant increased to165. Increasing in dielectric constant was attributed to the crystallization of the amorphous phase. The dielectric constant of BaTiO3 thick films produced by plasma spray was lower than that of sintering ceramic. Reduction in dielectric properties of deposited films was related to splats interface and lamellar structure of plasma sprayed coatings. تفاصيل المقالة -
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9 - Optical and Dielectric studies in zirconium(IV) tungstate nanoparticles prepared by chemical coprecipitation method
Beena Bhaskaran Manoj Sadanandan,Nanoparticles of zirconium(IV) tungstate are prepared by chemical co-precipitation method. Thecharacterizations have been carried out by TG/DTA, DSC, AFM, XRD, FTIR and UV-Vis spectrum. PLspectrum shows two emission bands at 350 nm and at 477 nm. The effects of frequenc أکثرNanoparticles of zirconium(IV) tungstate are prepared by chemical co-precipitation method. Thecharacterizations have been carried out by TG/DTA, DSC, AFM, XRD, FTIR and UV-Vis spectrum. PLspectrum shows two emission bands at 350 nm and at 477 nm. The effects of frequency on the dielectricbehavior and ac electrical conductivity have been studied. The dielectric constant is found to be 119.43 at1MHz. The ac conductivity is 7.29x10-8S/cm. تفاصيل المقالة
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