Yang L.Shen Y.Mi S.Fan J....
5页查看更多>>摘要：? 2021 Elsevier B.V.A new W–Cu potential has been established within the framework of the embedded-atom method (EAM) through the additional fitting of the structural energy differences between FCC and BCC structures of W and Cu. Based on this new potential, molecular dynamics simulations reveals that the lattice parameters of both BCC and FCC W–Cu solid solutions are bigger than those from the Vegard's law, and BCC and FCC W100-xCux solid solutions are thermodynamically more stable when 0 ≤ x ≤ 80 and 80 < x ≤ 100, respectively. Simulations also indicate that the solution of Cu in W would considerably decrease tensile strength and ductility of BCC W and a similar result could be obtained for the solution of W in FCC Cu. Furthermore, the derived lattice parameters, phase stability, heat capacity, and mechanical properties of W100-xCux solid solutions from the new potential are in accordance with other results from experiments, density functional calculation, and thermodynamic model in the literature.
原文链接:
NSTL
Elsevier
Gunderov D.V.Bhatt J.Prabhu Y.Srivastav A.K....
5页查看更多>>摘要：? 2021 Elsevier B.V.In the present investigation, we propose a theoretical approach to design the Zr-rich glass forming composition in Ni-free Zr-Cu-Al-Fe quaternary system under the thermodynamic framework. In this work, quaternary composition is designed by optimising chemical interaction and topological features among the constituent elements to determine enthalpy of chemical mixing (ΔHchem) and atomic size mismatch entropy (ΔSσ/kB) in a statistical framework of configurational entropy (ΔSconfig/R). Further, the effect of elemental Al and Fe addition in the Zr-Cu system on the glass forming ability (GFA) is analysed from thermodynamic viewpoint. Also, an attempt is made to understand the effect of Dy addition on thermodynamics and GFA of Zr-Cu-Al-Fe system. Subsequently, Zr62Cu22Al10Fe5Dy1 bulk metallic glass was synthesized for further investigation.
原文链接:- NSTL
- Elsevier
Chithambo M.L.Sob A.J.L.Kalita J.M.
5页查看更多>>摘要：? 2021 Elsevier B.V.Inter-electron-trap charge movement induced under phototransferred thermoluminescence (PTTL) in Al2O3:C,Mg annealed at 700 and 900 °C is reported. Such annealing modifies the emission spectrum and electron trapping states in Al2O3:C,Mg. The glow curve of Al2O3:C,Mg annealed at 700 °C has eight peaks at 46, 76, 100, 170, 199, 290, 330 and 375 °C respectively. In comparison, that of the sample annealed at 900 °C has nine at 49, 80, 100, 174, 206, 235, 290, 335 and 375 °C. The peaks are labelled I, II, III … in that order. Only peaks I-IV re-appear under phototransfer. The PTTL is analysed qualitatively as well as by computational and phenomenological models as systems of an acceptor and multiple donors. Point defects that likely contribute to emergence of PTTL are discussed and are deduced to lie mostly in the oxygen sub-lattice.
原文链接:- NSTL
- Elsevier
Epifano E.Hug G.Connetable D.
5页查看更多>>摘要：? 2021 Elsevier B.V.Nitrogen and carbon play an important role in the oxidation of Ti-Al intermetallic alloys in air. The insertion and diffusion of these elements in the γ-TiAl phase are investigated by first-principle computations. The accommodation of C and N atoms in several likely interstitial positions has been evaluated using density functional theory (DFT) calculations. The results show that both carbon and nitrogen prefer Ti-rich environments. Then, considering the possible jumps among the stable and metastable interstitial sites, the diffusion coefficients have also been obtained from ab initio calculations. According to the Transitional State Theory, in order to compute atomic jump rates, diffusion energy barriers and vibrational modes need to be known. Herein, barrier energies are obtained using the Climbing Image Nudged Elastic Band method. Vibrational properties are computed using the finite displacement method. Finally, diffusion coefficients are obtained solving the transport equation in the infinite time limit, using an analytical approach. The obtained results are compared to the diffusion of oxygen in γ-TiAl, investigated in previous studies. An anisotropic diffusion is obtained for all the interstitial species.
原文链接:- NSTL
- Elsevier
Aamir M.Yasmeen G.Ashiq M.N.Aleem W....
5页查看更多>>摘要：? 2021 Elsevier B.V.Co–Zr doped Ni ferrite substituted polyaniline (PANI) nanocomposites were prepared using polymerization reaction method. NiFeCo0.5Zr0.5O4 with 12.5%, 25%, 37.5% and 50% PANI (A1, A2, A3 and A4) were used to obtain better photocatalytic efficiency. XRD, UV/VIS, BET, and FESEM were employed to characterize the PANI/ferrite nanocomposites. The effect of reaction time and nanoparticle concentrations on the photocatalytic degradation were thoroughly evaluated. XRD analysis confirmed the phase of NiFeCo0·5Zr0·5O4ferrite, while FESEM analysis was performed to investigate the surface morphology of the nanocomposites. The crystallinity was increased with the Co–Zr doped Ni ferrite contents in the prepared nanocomposites. UV/VIS study was done to evaluate the optical properties. Shifting of peaks towards higher wave number in FTIR spectra evident the interactions between the polymer and nanoparticles. UV–Vis studies also confirm the interactions of dopant metals with polyaniline backbone chains. The surface area and porosity of the nanocomposites were concluded by BET and FESEM images. The kinetics studies of methyl orange were described by the Pseudo First-Order relation (best adjust R20.9947 for 50% w/w (A4)). The degradation efficiency was increased with the increase of Co–Zr ferrite contents which depicted the remarkable influences of nanoparticles in the nanocomposites. It is expected that the prepared PANI/NiFeCo0·5Zr0·5O4 nanocomposites are suitable photocatalyst for the removal of methyl orange in aqueous media.
原文链接:- NSTL
- Elsevier
Du F.Kuang J.Xiao Y.Liu L....
5页查看更多>>摘要：? 2021 Elsevier B.V.Sm3+, Ce3+ singly doped and Ce3+-Sm3+ co-activated LaSi3N5 were synthesized by a solid-state reaction method. The crystal structure, morphology and luminescent properties of the corresponding samples are characterized. The photoluminescence results demonstrate that LaSi3N5:Ce3+ phosphor has a broad band excitation spectra and emission spectra with peak at 418 nm, while LaSi3N5:Sm3+ phosphor demonstrates characteristics of linear excitation spectra with main peak locating at 407 nm. An apparent spectral crossover between the emission spectrum of LaSi3N5:Ce3+ and excitation spectrum of LaSi3N5:Sm3+ can be observed, pointing to the possibility of energy transfer from Ce3+ to Sm3+, which is further proved by the investigations of diffuse reflectance spectra, emission spectra, and fluorescence lifetime decay curves. The energy transfer efficiency reaches the maximum of 65.5%. The mechanism of energy transfer was determined to be electric dipole-dipole interaction. This study provides a new example for the development of efficient phosphors in Ce3+- Sm3+ codoped nitrides.
原文链接:- NSTL
- Elsevier
Parida B.N.Mohanty B.Parida R.K.Bhattacharjee S....
5页查看更多>>摘要：? 2021 Elsevier B.V.The conventional solid-state route method was adopted for the synthesis of the double perovskite Ba1.5Ca0.5FeVO6. The well define spikes that appear in the XRD profile of the investigated sample suggested the formation of a single-phase new compound. The structural refinement carried out through POWD and MAUD software suggested the material crystallize in the monoclinic phase having a space group of P21/m. The morphological investigation of the sample was carried out by field emission scanning electron micrograph (FESEM). The involvement of different vibrational modes such as stretching, bending, etc. as well as functional groups associated with the compounds was studied through Raman and Fourier transform infrared (FTIR) spectroscopic techniques. The electronic configuration and chemical valence state of the involved elements were investigated by incorporating X-ray photoelectron spectroscopy. The optical sensitivity and bandgap of the material were studied through UV–Visible spectroscopy. The dielectric properties of the material were investigated by monitoring the variation of dielectric parameters (dielectric constant and loss tangent) with frequency while non-destructive impedance and modulus techniques were adopted for electrical characterization. Besides, the AC and DC conductivity spectra were studied for a detailed investigation of electrical properties and the type of charge carriers in the material. The identification of ferromagnetism in the material at room temperature was done by M-H loop.
原文链接:- NSTL
- Elsevier
Gupta Y.Sinha M.M.Verma S.S.
5页查看更多>>摘要：? 2021 Elsevier B.V.In this paper, lattice dynamical properties and other properties such as structural, electronic band structure, and density of states of Full Heusler alloy ‘MnY2Ga’, are studied by using first-principles density functional perturbation theory and density functional theory. The calculated spin-polarization ratio for MnY2Ga is found to be ?31.6%, which signifies its false half-metallic character. The phonon dispersion spectra, phonon density of states, and different phonon modes have been determined for the first time using non-spin and spin-polarized calculations and discussed in detail. The lattice dynamical calculations confirm the cubic phase (L21) of MnY2Ga at the ambient conditions of pressure and spin plays a crucial role in vibrations of phonons. The present work reveals that spin-modifies the atomic interactions and structures, and results to give a flexible lattice, which will encourage further applications for the design of functional materials.
原文链接:- NSTL
- Elsevier
