Aldaoud, AnfalLemine, O. M.Ihzaz, N.El Mir, L....
9页查看更多>>摘要：We report the preparation, characterization, and heating efficiencies of undoped and Cobalt (Co)-doped maghemite (gamma-Fe2O3) nanoparticles (NPs) for magnetic hyperthermia applications. The structural, magnetic properties and heating ability of the as-synthesized NPs were fully characterized. XRD and Rietveld analysis showed the formation of single cubic phase of gamma-Fe2O3, where doping with Co did not alter either the crystal structure or the lattice parameter. It was found that Fe ions are tetrahedrally and octahedrally coordinated to oxygens and that Co ions occupy the octahedral sites in Co-doped samples. Magnetic measurements displayed increase of magnetic saturation (Ms) with increasing Co concentrations from 0 to 5% (53.14-67.49 emu/g), with negligible coercive field and remanence suggesting superparamagnetic behavior. Langevin model and the law of approach to saturation (LAS) were used to confirm superparamagnetism and to determine the effective anisotropy constant (Keff), respectively. Temperature rise under an alternating magnetic field (AMF) were conducted, indicating that all the samples have high heating efficiencies and reach hyperthermia temperatures (42 C) in relatively short times (3-10 min). Interestingly, gamma-Fe2O3 NPs reached 42 C in only-4 min, while 1-5% Co doped gamma-Fe(2)O(3-)NPs required 7-10 min to reach the same temperature. Surprisingly, SAR (122 W/g) and ILP (1.5 nHm2/kg) values of gamma-Fe2O3 NPs were found to be higher compared to Co-doped gamma-Fe2O3 counterparts, indicating better heating efficiency of gamma-Fe2O3 NPs. The mechanism of heating and plausible reasoning for this observation is discussed. Nevertheless, the ILP values for both gamma-Fe2O3 and 1-5% Co-doped gamma-Fe2O3 NPs (0.52-1.5 nHm(2)/kg) are in the range reported for commercial ferrofluids, proving their good heating efficiencies, and making them promising candidates for magnetic hyperthermia applications.
原文链接:
NSTL
Elsevier
Milyutin, V. A.Gervasyeva, I. V.Shishkin, D. A.Beaugnon, E....
8页查看更多>>摘要：The structure and crystallographic texture formation processes in two Fe-Ga magnetostrictive alloys during annealing of deformed samples under high magnetic field (HMF) 20 T have been studied. It was shown that the effect of the magnetic field on the structure transformation during annealing depends on the features of the recrystallization in alloys. In the case of recrystallization in a single-phase binary Fe-Ga alloy, the application of HMF along the rolling direction promotes the formation of <100> grains along this direction. This leads to a twofold increase in the magnetostriction of the polycrystalline sample. In the same alloy, but with the presence of particles of the second phase, HMF does not affect the texture. The reasons for this phenomenon were discussed. In addition, it was found that in both alloys, the application of HMF during annealing retards the processes of structure evolution.
原文链接:- NSTL
- Elsevier
Zhang, XinyueLi, WenjingGao, LiliCui, Xiangyue...
4页查看更多>>摘要：Herein, we have performed extensive swarm-intelligence structures searching simulations on the KSix (x = 4, 5, 6, 7, 8) compounds within the pressure range from 0 to 50 GPa. Seven crystal structures of potassium silicides are proposed, and the dynamic stability of these phases were explored in the corresponding pressure range. KSi4 was predicted to be stable, and it was found to have two phases, named C2/m-a and C2/m-b, respectively. As for KSi5, two thermodynamically stable phases were determined as C2/m and Imma, respectively. Above 1.33 GPa, the proposed monoclinic phase with C2/m is energetically favorable. With the increasing pressure, our proposed new Imma phase becomes energetically favorable at 16 GPa. For KSi6, it was determined that has the following space groups, Cmcm, C2/m and P-6/m. These findings provide insights for helping advance our understanding of the KSix compounds under high pressure.
原文链接:- NSTL
- Elsevier
Zhang, G. L.Lu, Q. M.Zhang, F. P.Yue, M....
9页查看更多>>摘要：The Formations, stabilities, evolutions of geometries, electronic states together with the spin polarization transitions involved with magnetic properties of the MnGa compound under c axis anisotropic stress are systematically studied within the framework of density functional theory analyzing method. The results show that the anisotropically geometric expansion can be induced under stress. There are five kinds of atomic distances within the compound, with larger distance values for Mn-Mn and Ga-Ga, and smaller distances for Mn-Ga. The induced atomic distance fluctuations are also anisotropic, corresponding to the anisotropic binding strength regulations. The compound under stress is more stable. The s orbital releases electrons, the p and the d orbitals accept electrons for Mn. The s orbital and the d orbital release electrons, the p orbital traps electrons for Ga. The Mn1 and Mn2, Ga1 and Ga2 have diversified configurations under stress. A transition of ionic state of Mn2 is observed. Electrons transfers occur between orbitals and species under stress. The MnGa has anisotropic conductor band structure. The effective mass of conduction band as well as shallow valence band are enhanced under stress. The electronic band experiences a transition from semimetal into metal. The s, p and d electrons form the conduction band and shallow valence band. The d electrons mainly form the deep valence band, too. The localization at-16.8eV of d electrons is weakened under stress. The Mnd electrons get less responsible for the spin state under stress. The Mn1 and Mn2 turn to exhibiting distinctively diverse profiles, the Ga1 and Ga2 turn to exhibiting the same profiles under stress. The Mn shows strong atomic magnetic moment than that of Ga.
原文链接:- NSTL
- Elsevier
Kapustianyk, V.Semak, S.Chornii, Yu.Bovgyra, O....
10页查看更多>>摘要：This work was devoted to the experimental investigations of the absorption spectra of (NH4)(2)CuCl4 x 2H(2)O crystals in order to obtain information about the variation of the chromophore group and related structural changes around the ferroelastoelectric phase transition at T-c = 200.5 K. It was shown that the anionic complex around Cu2+ ion possesses the shape of a flattened octahedron with the shortest distance O-Cu-O. The parameters of the elementary contours were found to manifest the noticeable anomalies in their temperature dependences at the phase transition point. The first principles calculations in the framework of the density functional theory confirmed the experimental data. The absorption edge in the UV-visible range of the spectrum was assigned to the charge transfer bands. The parameters of the absorption bands in the calculated spectrum within the range of 10000-16000 cm(-1) corresponding to the Cu2+ ions d-d transitions fairly well correlate with the data of experimental spectra.
原文链接:- NSTL
- Elsevier
Sharma, IshuJayaprakash, AthiraSharma, Pankaj
12页查看更多>>摘要：The effects of the addition of Ge on the optical and physical properties of a-Pb15Se85-xGex (x = 0, 3, 6, 9, 12 at. %) vacuum evaporated thin films are discussed in the given paper. An X-ray diffraction analysis of the films reveals no sharp peaks, indicating their amorphous nature. Transmission spectra of normal incidence were measured in the spectral window of 500 nm-2400 nm. An absorption edge shift has been observed with the addition of Ge at the expense of Se. Swanepoel analysis was applied to compute the refractive index values. Absorption losses were also calculated and discussed. The increase in Ge addition changes the refractive index and absorption coefficient. The bandgap transition is indirect and experimentally calculated using the Tauc-extrapolation method. Penetration depth and optical density were also calculated. WDD model was applied and static refractive index and WDD parameters were evaluated. Theoretical parameters viz. Cohesive energy, average heat of atomization, compactness, polaron radius were also calculated. Efforts were made to correlate obtained optical and physical parameters of the system.
原文链接:- NSTL
- Elsevier
Surani, AkshayDhruv, DavitZala, DivyarajsinhChudasama, D. K....
10页查看更多>>摘要：In this communication, structural, microstructural and low magnetic field influenced dielectric and impedance have been investigated for low cost chemically grown Bi0.85La0.15FeO3 thin film grown on FTO glass substrate by using sol-gel spin coating method. X-ray diffraction (XRD) reveals the successful growth of Bi0.85La0.15FeO3 film on FTO substrate. Surface morphology of the film has been examined by scanning probe method. Magnetoelectric (ME) properties of the film have been understood at room temperature. Magnetic field influenced dielectric behavior has been systematically investigated in the frequency range of 20 Hz to 2 MHz. The magnetic field induced alterations in the dielectric constant and impedance behavior at different frequencies confirm the complex nature of ME coupling between spin and lattice of BLFO film. Magnetic field dependent conductivity behaviors show a complex governance of charge carrier movements by the lattice disorder effect and spin alignment of iron ions in the BLFO lattice.
原文链接:- NSTL
- Elsevier
Moreira, A. C. L.Marques, L. S.
8页查看更多>>摘要：In this work we propose a theoretical study of odd-even effects in charge transport through a linear three terminal chain device. We use the Landauer approach, with the electronic structure treated at tight binding (TB) level and model the self-energy as an energy independent parameter. Moreover, we use decimation techniques to renormalize the system, reducing it into a 3 x 3 matrix, so as to make an analytical treatment. By varying the size of the chain, we alter not only the parity of the full system but also the parity of each possible pathway and show how odd-even effect appears in the transmission function, local density of states and the behavior of the electrical current as function of the parity. Our theoretical approach reveals, in a clear way, how the parity of each branch competes with the parity of the full system to the conductance values near the Fermi level.
原文链接:- NSTL
- Elsevier
Wang, JianchuanLiu, LibinZhang, WeibinDang, Feng...
6页查看更多>>摘要：Lattice defects are common in electrode materials and may affect their structural stability and electrochemical performance. Here we use first-principles calculations based on density functional theory to investigate native cation point defects in spinel LiTi2O4, a potential candidate for anode material in lithium ion batteries. We consider vacancies, interstitials, antisite defects, Frenkel defects and some defect pairs. Our calculations show that Li interstitial, Ti interstitial, Li Frenkel defect and Li antisite are low-energy defects, and thus they would be detectable in LiTi2O4, while cation vacancies and Ti Frenkel defect are hard to form due to their high formation energy. Binding energies are calculated to illustrate whether the isolated defects will clustering or not. In addition, the effect of native defects on migration of Li is studied. We find that Li antisites can make the migration barrier of Li interstitial decreasing significantly.
原文链接:- NSTL
- Elsevier
