Wang, YiLiu, YingZhao, DongYang, Shuai...
14页查看更多>>摘要：In this paper, the wave dispersion in a light-sensitive liquid crystal elastomer porous phononic crystal is investigated. An opto-mechanical indirect-coupling strategy is proposed to investigate the coupling optovariation of band structures. Firstly, the opto-deformation of the phononic crystals is analyzed, and then the band structures in the deformed lattice is determined. The effects of light intensity and director orientation on the properties of absolute band gaps are discussed. The results show that the absolute band gap structure depends on the light intensity, the angle between the light and the director, as well as the porosity. These unique properties promise prospective applications in the intelligent tuning of band structure in pononnic crystals.
原文链接:
NSTL
Elsevier
Civalek, OmerUzun, BusraYayli, Mustafa Ozgur
10页查看更多>>摘要：In the present study, free torsional and axial vibrations of porous nanorods with torsional, axial elastic boundary conditions are presented via Eringen's nonlocal elasticity theory. This theory takes into account the small size effect into the differential formulation due to dealing with nano-sized structures. Even though free axial and torsional vibrations based analysis of nanorod is a widely investigated topic, there are only few researches which exist in the scientific literature pertaining to the vibration analysis of porous nanostructures with nonrigid (deformable) boundary conditions. This study brings a contribution to the literature by presenting both porosity and small size effects with deformable boundary conditions. It is also planned to examine the effects of porosity and small size in detail. A model that allows to examine all of these effects within the framework is created within the scope of this study. To this end two torsional and axial springs are attached to the porous nanorod at both ends separately. Present model bridges the gap between deformable and non-deformable (rigid) boundary conditions. An eigen-value problem is constructed including torsional and axial coefficients by using Stoke transformation and the Fourier sine series. The novelty of this work is that it seeks to construct a general eigen value algorithm for the torsional and axial vibration frequencies of the porous nanorods subjected to the deformable and rigid boundary conditions for the first time. Moreover, the effects of some parameters such as porosity index, axial and torsional restraints on the free vibration frequencies are investigated and some conclusions are drawn.
原文链接:- NSTL
- Elsevier
Hasan, MariamZawar, SidraMustafa, Ghulam M.Ghaffar, Abdul...
7页查看更多>>摘要：To explore the electrochemical performance, we synthesized a series of Ni-substituted ZnMn2O4 using sol-gel auto-combustion route. The formation of the tetragonal phase for ZnMn2O4 and its transformation into a cubic phase upon Ni substitution is confirmed by the X-ray diffraction technique. Morphology analysis revealed that average particle size is increased from 150 to 250 nm when contents of Ni are increased from x = 0.0 to x = 1.0, respectively. Employing cyclic voltammetry and galvanostatic charge and discharge test, it is observed that pure ZnMn2O4 has a specific discharge capacity of 11.2 F/g which decreased to 8.49 F/g for ZnMn2O4. The tuning of this electrochemical performance is accredited to its hierarchical structure which facilitates charge transfer, large reaction surface area, and good structure stability. All these results validate that Zn1-xNixMn(2)O(4) composites are a suitable candidate as electrode material in supercapacitors.
原文链接:- NSTL
- Elsevier
Yin, Kai-WenDie, DongYang, Ji-Xian
8页查看更多>>摘要：The ground-state structures, electronic properties and spectra of Ticn (n = 3-16 and c = 0, +/- 1) clusters have been investigated based on density functional theory (DFT) and CALYPSO structure prediction. Geometry optimizations show that the neutral, cationic and anionic titanium clusters have the same growth pattern. The pentagonal bipyramid plays an important role in the growth process. Analysis of electronic properties shows that the thermal stability of cationic and anionic clusters is greater than that of neutral cluster. The pentagonal bipyramid and icosahedron clusters have relatively high stability. Chemical activity of titanium clusters decreases with the cluster size. The preferred dissociation pathway of Ti-n(+) clusters is the loss of a single Ti atom to form Ti(+)n(-1). Optical absorption of Tin clusters and infrared and Raman spectra of Ti+n clusters have been simulated and can be used for their structural identification. The ground states of Ti?n clusters have been determined by comparing experimental and theoretical photoelectron spectra.
原文链接:- NSTL
- Elsevier
Nguyen Hong QuangNguyen Que Huong
5页查看更多>>摘要：Currently in literature, "charged exciton"and "trion"are often confused with each other and mostly considered the same. In this work we show that these terms might actually describe different quasi-particles. Energies and binding energies of both charged excitons and trions in 2D parabolic quantum dots have been calculated as functions of confinements of charge carriers in a quantum dot, using the unrestricted Hartree-Fock method. It is shown that the binding energies of the charged exciton and the trion behave differently in regard to the ratios of the confinements of the electron and the hole. The effect of the external magnetic field on the binding energies of charged excitons has also been considered.
原文链接:- NSTL
- Elsevier
Alharbi, Seham R.Qasrawi, A. F.Algarni, Sabah E.
7页查看更多>>摘要：Herein, thin films of SeO2 coated onto glass and Ag thin film substrates are studied and characterized. The films which are prepared by a vacuum evaporation technique, displayed Ag-metal induced crystallization process. The grown films are composed of tetragonal structure of SeO2 as major phase and orthorhombic beta - Ag2Se as minor phase. The optical studies showed that the films exhibit an energy band gap of 3.69 eV. In addition, the analyses of the dielectric dispersion spectra indicated the nonlinear character of dielectric response. The SeO2 films response to oscillatory electromagnetic field is accompanied with drift mobility values in the range of 5.02-12.06 cm2/Vs. Moreover, polycrystalline SeO2 films coated onto Ag substrates are found appropriate for use as negative capacitance (NC) sources in the frequency domain of 0.41-1.80 GHz. Accompany with the NC effect, negative conductance (NG) effect was observed near 0.410 GHz and near 1.53 GHz.
原文链接:- NSTL
- Elsevier
Liu, Tian-LunHuang, Yu-HongWei, Xiu-MeiZhang, Jian-Min...
7页查看更多>>摘要：Despite pure pyrite FeS2 has a very high optical absorption coefficient about 10(5)cm(-1), its smaller band gap about 0.95eV leads to a lower than 3% photoelectric conversion efficiency and thus limits its semiconductor photovoltaic applications. In this paper, we make a comparison study of the structural, electronic and mechanical properties of the pure pyrite FeS2 and oxygen doped pyrite FeO0.25S1.75 under pressure range of 0-25 GPa by first-principles calculations within GGA + U method. With increasing the pressure from 0 to 25 GPa, the band gap of the pure pyrite FeS2 oscillation decreases from 0.936eV at zero pressure to 0.682eV at 25 GPa and thus is not suitable for semiconductor photovoltaic application. Fortunately, the band gap of the oxygen doped FeO0.25S1.75 increases firstly from 1.080eV at zero pressure to the maximum value of 1.290eV at 13 GPa and then decreases slightly but is still larger than that of the pure pyrite FeS2. Especially, this maximum band gap value of 1.290eV at 13 GPa closes to the value of 1.340eV of Shockley-Queisser limit for semiconductor photovoltaic applications. Furthermore, the oxygen doped FeO0.25S1.75 is mechanical stable under pressure range of 0-25 GPa based on Born stability criteria. Our study shows that it is feasible to further increase the band gap of the oxygen doped pyrite FeO0.25S1.75 by applying a suitable pressure.
原文链接:- NSTL
- Elsevier
Kozuka, ShunsukeUeda, JumpeiTanabe, Setsuhisa
6页查看更多>>摘要：Mn4+ ions show red to deep-red luminescence due to the E-2 ->(4)A(2) spin-forbidden transitions in several host materials. Especially, Mn4+-doped LaAlO3 with perovskite structure shows the deep red luminescence with a quite long wavelength around 730 nm in the first biological window. In this study, we investigated the temperature dependence of the photoluminescence spectra of Mn4+-Ca2+ co-doped LaAlO3 (LAP: Mn4+-Ca2+) and a possibility as a thermometer based on the energy shift of zero-phonon-line (ZPL) and the luminescence intensity ratio (LIR) of thermally coupled ZPL and anti-Stokes phonon sideband (PSB). As a result, the LAP: Mn4+-Ca2+ phosphor shows the continuous energy shift of ZPL with temperature and three different temperature dependences of the LIR by selecting different two luminescence bands, which means that the LAP: Mn4+-Ca2+ phosphor has four different thermometric functions in one phosphor. All the thermometers show a good relative sensitivity and wide working temperature range from 100 K to physiological temperature.
原文链接:- NSTL
- Elsevier
Farsaci, FrancescoTellone, EsterScala, Angela
12页查看更多>>摘要：The paper presents for the first time an in-depth theoretical magnetic characterization of cobalt ferrite nano particles (CoFe2O4) by using the thermodynamic approach of non-equilibrium with internal variables. Considering that a complete knowledge of the structure and properties is crucial to design a material for a specific application, a complete thermodynamic characterization of magnetic properties turns out to be useful for a plethora of technological and biomedical purposes. The non-equilibrium thermodynamics is exploited to calculate the internal variables as a function of the perturbation frequencies. Our results allow to fully characterizing the investigated material in terms of magnetization by orientation and by deformation (M-(1) and M-(0)), magnetic field B-(1), magnetization displacement current (E), entropy production (sigma), phenomenological coefficients (L-(0,L-0) and L-(1,L-1)) and state coefficients (a((0,0)), a((1,1))). CoFe2O4 has been selected as a proof of concept; our theoretical investigation and parameters are applicable to all the para-and ferromagnetic materials, including biomolecules and biological tissues allowing to compare healthy and pathological behavior, subjected to a variable magnetic field for which it is possible to conceive a linear approximation.
原文链接:- NSTL
- Elsevier
