Beyazay, EmreKarabul, YasarKilic, MehmetKorkut, Sibel Eken...
8页查看更多>>摘要：This study focuses on both synthesis and structural characterization of polycarbazole/barium oxide (PCz/BaO) nanocomposites and the determination of their frequency-based electrical properties such as complex permit-tivity, tangent loss, and alternating current (ac) conductivity. While PCz was synthesized by using carbazole monomers, BaO nanoparticles (NPs) were obtained by using the co-precipitation method. PCz matrix and BaO NPs were examined by scanning and transmission electron microscopes, X-ray diffraction, and Fourier Trans -formed Infrared Spectroscopy methods. The electrical properties of the PCz/BaO nanocomposites showed that the energy storage ability of the PCz can be improved with the addition of BaO NPs up to 10 wt% at the low frequencies. Furthermore, the 2.5 wt% BaO NPs contribution causes an increase in epsilon' and a decrease in epsilon " of PCz. Additionally, it has been determined that BaO NPs doping significantly increases the ac conductivity of the PCz matrix in the low-and mid-frequency regions.
原文链接:
NSTL
Elsevier
Manori, SamtaChandra, Ramesh
6页查看更多>>摘要：We report spin-glass (SG) behavior and large exchange bias effect at low temperature (-2 K) in Fe-doped hexagonal-YMnO3 (YMn0.8Fe0.2O3) thin film. The thin films of YMnO3 and YMn0.8Fe0.2O3 are deposited on Pt (111)/Al2O3(0001) substrate by pulsed laser deposition method. The temperature dependent magnetization measurements show a characteristic peak for YMn0.8Fe0.2O3 film indicating the presence of SG state as confirmed by memory effect measurements. The hysteresis loops reveal high coercivity in YMn0.8Fe0.2O3 as compared to YMnO3 thin film. Field cooled hysteresis loop measurements at 2 K show the presence of exchange bias in YMn0.8Fe0.2O3 thin film. Maximum exchange bias of ~909 Oe has been observed for hysteresis loop with cooling field of 20 kOe at 2 K. The exchange bias is further confirmed by training effect as well as negative and positive field cooled hysteresis loops. Exchange bias effect in YMn0.8Fe0.2O3 thin film can be attributed to the interaction between spin-glass/Anti-ferromagnetic phases.
原文链接:- NSTL
- Elsevier
Zarhri, ZakaryaaCocom Dzul, Martin BladimirZiat, YounesOubram, Outmane...
6页查看更多>>摘要：Currently, the most used transparent conductive oxide (TCO) is the indium tin oxide (ITO). The need for a material that can replace this TCO comes in many studies. Among these materials, we have discussed zinc oxide (ZnO). This work is carried out using full-potential linear augmented plane wave (FP-LAPW) and implemented in the Wien2k. Since the ZnO alloy has different structures, this study aims to discuss the optoelectronic behavior of the F doped ZnO with its different phases and the doping concentration variation where the amount of F is 3.125%, 6.25% and 12.5%. in the visible light range. The comparison between the Rock Salt and Zinc Blend structures gives a starting point to be compared with the third structure which is Wurtzite. TB-mBJ was applied to compare the promising results found by the GGA approximation. Its optoelectronic properties make fluorine-doped ZnO a promising candidate for optoelectronic applications.
原文链接:- NSTL
- Elsevier
Ebrahimi, S. A. SeyyedMohseni, S. M.Talaeizadeh, M.Jamilpanah, L....
6页查看更多>>摘要：The magnetic-field-induced resistance switching of a granular composite containing Co2FeSi with Mn and Al2O3 was investigated for the first time. Field emission scanning electron microscopy (FESEM) images showed a mean particle size of about 100-150 nm. Different compositions of materials showed different Magnetoresistance (MR). Positive and negative MR responses were observed in the samples while the possible mechanisms were also discussed. The electric resistance of the samples increased by the Al2O3 amount and tunneling became the dominant electron drift mechanism. The electron conductance percolation threshold of the composite was found to be around 20 to 30 wt% Al2O3 in which the MR reached a maximum value. This paper is part of a series of systematic investigations on these novel composites publishing for the first time.
原文链接:- NSTL
- Elsevier
Ghorbani, H.Eshraghi, M.Sabouri Dodaran, A. A.
10页查看更多>>摘要：The magnetization of CoFe2O4 nanoparticles is often less than the bulk value of 3.6 mu B (86 emu/g), corresponding to an inverse distribution of cations in the spinel structure. This paper investigated the Cd doping on cobalt ferrite nanoparticles' structural and magnetic properties. Cobalt ferrite nanoparticles doped with cad-mium (Co1-xCdxFe2O4, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by using hydrothermal method. X-ray diffraction (XRD) analysis confirmed cubic spinel structure, and the crystallite size is estimated at around 56-59 nm. Micrographs obtained by scanning electron microscopy (SEM) showed an average particle size of about 60 nm, which is in agreement with the XRD analysis. The absorption band nu(1) for samples obtained from the infrared spectrum (FTIR) varies from 586 up to 570 Cm-1 by Cd doping, indicating Cd's replacement on the tetrahedral site. Magnetization values of 71 and 81 emu/g are obtained for x = 0 and x = 0.1 samples, respectively. But the magnetization decreased as the amount of Cd doping further increased due to the decreasing superexchange interaction between tetrahedral and octahedral sites. The rearrangement of Fe3+ and Co2+ cations on tetrahedral and octahedral sites and spin disorder at the surface of nanoparticles can reduce the magnetization below the bulk value. The coercivity field (Hc) value of 1.1 kOe is obtained for the x = 0, and the Hc values decrease with Cd doping. This is due to the decreasing magnetocrystalline anisotropy by substituting cobalt with cadmium.
原文链接:- NSTL
- Elsevier
Ghorai, ArunodayGhorai, Amitava
6页查看更多>>摘要：The parameters of Heine and Abarenkov model potential have been computed for 21 face centered cubic (fcc) closed pack crystals and a comparison is made with their magnitudes to the Ashcroft model potential. The magnitudes of monovacancy and divacancy formation energy are calculated for different fcc crystals and compared with the literature. Huge values of divacancy formation energy and divacancy binding energy in some higher valence fcc metals are attributed to the probability of instability of these defects there. Lastly, the changes in monovacancy formation energy and divacancy formation energy in presence of an impurity in three simple metals Cu, Ag, Au are calculated.
原文链接:- NSTL
- Elsevier
Neelima, G.Mahesh, T.Manikanthababu, N.Pathak, A. P....
7页查看更多>>摘要：We present here the effects of swift heavy ion irradiation on the optical and structural properties of Germanium (Ge) nanoparticles (NPs) synthesized by using laser ablation of bulk Ge wafer in liquids. The Ge NPs have been irradiated with 120 MeV Ag ions of various fluences ranging from 5 x 10(12) to 1 x 10(14) ions/cm(2). The effect of ion irradiation on optical and structural properties of the Ge NPs has been studied with transmission electron microscopy (TEM), Raman scattering, and photoluminescence (PL) emission measurements. We have observed a decrease in the average size of the Ge NPs upon increasing the fluence of irradiation, amorphization at high fluence, and smaller NPs started to grow in the vicinity of larger sized NPs under ion irradiation. Therefore, the proper selection of fluence can be tuned to modify the existing NPs and synthesize new NPs. The NPs became amorphous at the higher fluence with the core remaining crystalline while the shell transformed into an amorphous phase. From Raman scattering results, the shift observed in peak position and the increase in the broadening in the Ge phonon vibrational peak indicates a reduction in NPs size. The PL emission is also blue shifted upon increasing the irradiation fluence.
原文链接:- NSTL
- Elsevier
Gupta, Manoj KumarSharma, CharuKashyap, Deepak KumarChaturvedi, Ashish Kumar...
8页查看更多>>摘要：Highly crystalline zeolite nanoneedles were synthesised using industrial fly ash waste particulates using hydrothermal method for the first time. X-Ray diffraction result confirmed the formation of 13X crystalline zeolite nanoneedles. Elemental analysis of zeolite was investigated using X-Ray fluorescence spectroscopy technique. HR-TEM exhibits the crystalline nanoneedles like morphology with length of 50-300 nm and diameter of 30-40 nm. In, UV-ViS study, absorption cut-off band at 264 nm and optical band gap of 2.8 eV were obtained. The zeolite nanoneedles exhibits high refractive index of 4.5 at 264 nm. Ultra high electrical dielectric constant of 99151 was observed at low frequency of range 30 Hz. Such high dielectric constant of fly ash derived zeolite nanoneedles was almost 2450 times higher than bulk zeolite. Our results demonstrate a green synthesis method of zeolites nanoneedles from fly ash. The present finding shows its potential application in charge storage, optoelectronics devices and molecular sieving.
原文链接:- NSTL
- Elsevier
AL-Akhras, M-AliShakhatreh, Musab N.Chamroukhi, HelaTelfah, Ahmad...
8页查看更多>>摘要：Nanocomposite films of hosted protonated polyaniline (PANI/CSA) in polyethylene oxide (PEO) and incorporated with silver nanoparticles and silver nitrate (AgNPs-AgNO3) were deposited on activated quartz substrates by spin coating technique. Deduced refractive index from UV-Vis spectrophotometry experiments falls in the range of 1.5-2.0 for undoped films, while for the nanocomposite films ranges between 1.7 and 2.1 due to the effect of AgNPs-AgNO3 incorporation. Scanning electron microscopy observations reveal that the typical PANI crystalline structure vanishes gradually with increasing AgNPs-AgNO3 content and the nanocomposite optical band-gap decreases with increasing concentration of AgNPs-AgNO3. An amorphous state is dominant in all nanocomposite films. The electrical conductivity increases with increasing dopant content due to polaron formation and increased concentration of Ag ions at concentrations below 60 wt.% of AgNPs-AgNO3 with respect to PANI/CSA. From fitting the data to a Sigmodial/Gomperz function for concentrations in the range of 100-360 wt.% it was found that the nanoparticles percolation was the dominant electrical conduction mechanism.
原文链接:- NSTL
- Elsevier
Yang, XinChen, YugeChen, Bin
6页查看更多>>摘要：We investigate the spin excitation spectrum and the thermodynamic properties of the XXZ anisotropic ferrimagnetic spin-(1/2, 1) chain under the presence of a magnetic field using the Villain transformation method. The effect of the XXZ anisotropic parameter and external magnetic field on the thermodynamic observables are calculated at finite temperature. The energ y spectra exhibit the coexistence of a gapless branch and a gapf u l branch, both of them are sensitive to the change of XXZ anisotropic parameter. The gapless branch exhibits a V-shape structure, while the gapf u l branch is reversed and presents an omega-shape for the XY model which is completely different from previous results for the XXZ model. Thermodynamic quantities such as free energy, internal energy, entropy, specific heat and magnetization are present. These findings for the isotropic case are compared with the results calculated by the other established methods and it turns out that Villain transformation we l l describes this system at low temperature.
原文链接:- NSTL
- Elsevier
