Tantardini, ChristianGonze, Xavier
8页查看更多>>摘要：Ga(1-x)Inx N alloys, widely employed to produce light-emitting diodes, exhibit a bowing of the band gap as a function of concentration x, and a luminescence spectral width which differs from the expected value of 1.8 kT. Through first-principles calculations, based on many-body perturbation theory and density-functional theory with a meta-GGA exchange-correlation functional, we explore jointly these effects, in an exhaustive set of Ga(1-x)Inx N supercells with 16 atoms. We disentangle the bowing due to the average volume change with the one due local atomic configuration and local relaxation. The first one account for about 40% of the bowing, despite that fact that the change of volume with respect to concentration is nearly linear (Vegard's law). The computed bowing parameter is 1.39 eV. The experimental broadening between 3 kT and 8 kT, not examined theoretically until now, is well accounted by local atomic configuration changes and lifting of the degeneracy of the top of the valence band.
原文链接:
NSTL
Elsevier
Limberkar, ChaitanyaSom, N.Patel, K. D.Solanki, G. K....
9页查看更多>>摘要：A detailed study of phonon properties of SbxGe1-xSe (x = 0.00 and 0.15) crystals is demonstrated here. DVT technique was employed for crystal growth. Powder XRD confirmed the phase-singularity and revealed the structural minutiae of the grown materials. The surface morphology of the crystals was studied under a highresolution microscope. Room temperature Raman spectroscopy revealed a blue shift in the out-of-plane mode (B3g) and in-plane modes (Ag(1) and Ag(2)) of GeSe with Sb mixing. Further, the temperature-dependent Raman spectroscopy showed a monotonous red-shift and softening of modes as the temperature increases from 103 K to 298 K. The first order temperature coefficients for peaks B3g and Ag(2) are calculated. Shifting of modes pertaining to laser-power is also recorded for room temperature, and thermal conductivity of the crystals is determined. A strong anisotropy is found in the thermal conductivity for out-of-plane and in-plane modes for both crystals.
原文链接:- NSTL
- Elsevier
Chen, BoLi, Zi-RunCui, Wen-Li
7页查看更多>>摘要：This work investigates electrostatic switch of magnetic anisotropy in the composite with iron-metal granule and barium-titanate matrix theoretically. As the spontaneous polarization is switched downward or upward in barium-titanate matrix, the parallel or perpendicular magnetizing is preferred in iron-metal granule respectively. This demagnetizing anisotropy originates from the long-range electrostatic interaction in matrix body, which induces the inharmonic magnetic moment on granule surface. The effects of position bias and composite size are delicately studied. The cross-section map displays distorted electric polarization in barium-titanate matrix, and demagnetizing energy gradient in iron-metal granule. This work predicts the electrostatic switch of magnetic anisotropy in metal/oxide composite, which would develop the integrated device and functional material.
原文链接:- NSTL
- Elsevier
Misra, Sushil K.Salahi, Hamid Reza
13页查看更多>>摘要：A novel doubly rotating frame (DRF) technique has been exploited to calculate three- and four-pulse DEER signals for a system of two dipolar-coupled nitroxides. The three-pulse DRF technique is illustrated for the case, wherein the relative intensity of the peak, appearing at +/- d/2, is compared with that of the peak at +/- d, where d = 23 D (D = dipolar-coupling constant, as a function of B1, the amplitude of the pulses. It is found for three-pulse DEER signals that for the commonly used B1 fields the three-pulse DEER sequence is capable of measuring distances between the two nitroxides of the biradical corresponding to d <= 8 MHz, or distances r >= 18.7 angstrom. As for the four-pulse DEER signal, using the distribution of the distance between the nitroxide radicals, determined experimentally, the simulated DEER signal shows excellent agreement with the experiment.
原文链接:- NSTL
- Elsevier
Khan, Muhammad IsaGillani, S. S. A.Gadhi, M. AsgharBoukhris, Imed...
9页查看更多>>摘要：Physical characteristics of new quaternary Heusler alloys (QHAs) CoZrVZ (Z = Al, Ga, In, Sn) are determined employing first-principles calculations. Perdew-Burke-Ernzerhof (PBE) exchange and correlation functional treated with generalized gradient approximation (GGA) within full potential linearized augmented plane wave (FP-LAPW) method. Structural parameters are obtained through geometry optimization process for three nonequivalent configurations and Type I is found the most stable. Calculations for magnetic phases i.e. ferromagnetic (FM), anti-ferromagnetic (AFM) and non-magnetic (NM) are performed. Elastic, thermal and magnetic properties are investigated. All alloys are half-metallic (HM) in nature and magnetic moments are in well agreement to Slater-Pauling rule. The estimated Curie temperature (Tc) is well above the room temperature. The mechanical parameters confirmed that all alloys except CoZrVSn are stable and have ductile nature. Thermal properties predicted that all alloys have high melting temperature (Tm). All determined characteristics envisaged that these QHAs are suitable for technological and spintronic applications.
原文链接:- NSTL
- Elsevier
Arif, Sk MdRoy, DebiGhosh, Manas
16页查看更多>>摘要：Current inquiry explores the time-dependent quantum adiabatic switching (TDQAS) of impurity doped quantum dot (QD) under the aegis of Gaussian white noise (GWN). The QAS has been performed among the impurity modulated states of QD using several switching functions (SFs). The time-evolution of switching has been monitored with the help of overlap function and quantum information entropy (QIE). The SFs appear to recover the impurity-modulated eigenstates of QD corresponding to the final Hamiltonian starting from the analogous QD eigenstates corresponding to the initial Hamiltonian. The switching paths have been found to be comprising of important physical attributes of overlap function and QIE. These subtleties of the switching paths and the efficiency of switching/recovery depend on the nature of the SF itself and the characteristics of noise. The study deems importance since impurities have become inalienable part of QD systems for immense technological applications where presence of noise could invite additional delicacies.
原文链接:- NSTL
- Elsevier
Sustaita-Torres, I. A.Madrigal-Melchor, J.Sanchez-Arellano, A.Ariza-Flores, D....
7页查看更多>>摘要：In this article we report a novel characteristic in the dispersion relation for dielectric-graphene photonic crystal, resulting from the modulation of the chemical potential (mu(g,j)) of the graphene sheets in the unit cell that form the entire optical structure. The photonic dispersion relation of the system is obtained employing the transfer matrix formalism taking into account the intra and interband contributions of the optical conductivity of graphene. The chemical potential of each graphene sheet is distributed with discrete values following envelope functions such as Gaussian, linear, Lorentzian and Poschl-Teller. We found that this kind of dielectric-graphene photonic crystal shows the formation of spikes in the dispersion relation due to the discrete values of chemical potential in its unit cell. The spikes are located in the frequency positions which correspond to 2(mu g,j) for each distribution and can be modulated by optical and geometric parameters.
原文链接:- NSTL
- Elsevier
Shatooti, S.Mozaffari, M.Reiter, G.Zahn, D....
11页查看更多>>摘要：Zinc substituted spinel ferrite nanoparticles are appropriate for magnetic fluid hyperthermia. Stable suspensions of Zn2+ substituted magnetite (ZnxFe3-xO4, 0 < x < 0.20) nanoparticles in aqueous solutions (pH 5.5) were synthesized by means of co-precipitation approach, using citric acid (CA) and pluronic F127 as surfactants for hyperthermia application. The specimens were characterized by different methods. XRD patterns of the precipitates confirmed that all specimens have single phase cubic spinel structures and their lattice parameters increased as Zn2+ content increased. Mean crystallite sizes of the uncoated specimens were determined to be around 28 nm, using Scherrer's formula. By increasing the Zn2+ content, Curie temperature of the uncoated specimens reduced from 545 to 410 degrees C monotonically caused by reduction in super-exchange interactions. Room temperature saturation magnetizations of the uncoated specimens increased to 98.8 emu/g for x = 0.10 initially, and then decreased to 79.6 emu/g for x = 0.20. It is attributed to the replacement of paramagnetic Fe3+ ions by diamagnetic Zn2+ ones and spin canting. FTIR spectra reconfirmed formation of pure magnetite and Zn2+ substituted magnetite nanoparticles and also proved the presence of ligands on the surface of the nanoparticles. TEM investigation showed that mean particle sizes of the coated nanoparticles were in the range of 35-40 nm. The obtained ferrofluids showed a good stability in aqueous medium (pH 5.5) and according to the room temperature magnetic measurements, heating efficiency is scarcely released due to relaxation processes. Maximum obtained specific loss power (SLP) was 539 W/g and that of intrinsic loss power (ILP) was 7.26 nHm2/ kg for x = 0.05 (f = 290 kHz, H = 16 kA/m) with a nanoparticle concentration as low as 1.2 mg/ml, which is a promising candidate for magnetic hyperthermia applications potentially.
原文链接:- NSTL
- Elsevier
Yusuf, BashirHashim, Md RoslanHalim, Mohd Mahadi
6页查看更多>>摘要：The selective hole nature of MoOx is described by its high-level work function, which creates band alignment at the MoO3-Si heterointerface that turns the surface to inversion. However, its low conductivity and carrier concentration hinder the material predicted theoretical efficiency. Attempts to enhance the performance of the MoO3 was made by doping graphene oxides (GO) using the spray pyrolysis technique. The GO doping concentrations were varied in the range of 0-3 wt %. The properties of the pure MoO3 and chemically GO-doped MoO3 films were analyzed, and the efficiency variations and stability of the pure and GO-doped MoO3/n-Si solar cells were presented. The films doped with 2 % GO showed a higher concentration of 7.41 x 10(19) cm(-3) and a low resistivity of 40.16 Omega cm. This attributed to the improvement of the solar cell's parameters with, V-oc = 484.34 mV, J(sc) = 10.12 mA/cm(2), FF = 66.21 % and eta = 3.26 %.
原文链接:- NSTL
- Elsevier
Qashou, Saleem, IAli, Atif MossadSomaily, H. H.Algarn, H....
10页查看更多>>摘要：Ge25Se75 chalcogenide films have been prepared using thermal evaporation method. X-ray diffraction (XRD) analysis shows polycrystalline natureof the annealed Ge25Se75 chalcogenide films at 340 degrees C. The significant transmittance of Ge25Se75 films at 1000 nm suggested the using of this material as an effective color filters. The indirect transition is the adopted mechanism of the electron transition for the as-deposited and the annealed Ge25Se75 films. The optical band gap energy (Eg)was found to be increased as the annealing temperature increases. In the regime of the normal dispersion, the single oscillating energy(E0), the dispersion energy (Ed) values and the dielectric constant (epsilon infinity)for the as-prepared and annealed films were calculated. In the transparent region, the lattice dielectric constant (epsilon L) was found to be decreased as the annealing temperature increases. Moreover, the measurements of the nonlinear optical parameters of these films at different annealing temperatures verify the possible using of thischalcogenide glass as a promised candidate material for optical applications.
原文链接:- NSTL
- Elsevier
