Mehmood S.Ali Z.Khan I.Ahmad I....
5页查看更多>>摘要：? 2021 Elsevier B.V.Structural, elastic, electronic and magnetic properties of the transition metals based perovskites SrTMO3 (TM = Mn, Fe, Co, Tc, Ru, Rh, Re, Os, Ir) are investigated using advanced exchange-correlation methods based on density functional theory (DFT). The calculated structural parameters are found consistent with the experiments. The elastic properties reveal that these compounds are anisotropic, mechanically stable and ductile except SrMnO3. Electronic properties show that the strong hybridization between TM-d and O-2p states at the Fermi level make these compounds metallic expect SrMnO3 which is half-metal. The electrical resistivity indicates that these compounds are good conductors at room temperature. Magnetic ordering and magnetic susceptibility show that SrMnO3, SrFeO3 and SrTcO3 are G-type antiferromagnetic; SrCoO3, SrRuO3 and SrOsO3 are ferromagnetic, whereas SrRhO3, SrReO3 and SrIrO3 are paramagnetic/non-magnetic compounds. The study also confirms that TM-3d perovskites are strongly correlated electron systems while spin-orbit coupling effect is dominant in TM-5d perovskites.
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Elsevier
Kong Z.Duan Y.Qu D.Bao L....
5页查看更多>>摘要：? 2021 Elsevier B.V.Elastic constants, elastic anisotropy and thermal properties of heavy Fermi compounds CePtSix were computed by first-principles calculation based on density functional theory. We calculated the elastic constants of CePtSix compounds using the Viogt-Reuss-Hill approximation method. Vickers hardness is calculated by theoretical model. By introducing the 3D surface construction and its projection of the elastic modulus, we get the elastic anisotropy ranking of CePtSix. The arrangement of anisotropy in bulk modulus is CePtSi > CePt Si2>CePt Si3, meanwhile the sequence of Young's modulus is CePtSi > CePtSi3>CePtSi2. Moreover, the order of Debye temperature is CePtSi3>CePtSi2>CePtSi, indicating that CePtSi3 possesses the strongest bond strength and largest thermal conductivity.
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- Elsevier
Shrivastava A.Singh S.Saini S.
5页查看更多>>摘要：? 2021 Elsevier B.V.In this manuscript, we have investigated the electronic and optical properties of Stanene and hexagonal Boron Nitride (Sn/h-BN) heterostructure using the Projected Augmented Wave (PAW) method within the framework of density functional theory (DFT). van der Waals forces are also considered to counter the inter-layer interactions between Sn and h-BN. The significant band gap opening has been observed in Sn/h-BN heterostructure compared to pristine Stanene (Sn). However, the band gap is much lesser than the Boron Nitride (h-BN). In order to use the proposed structure in futuristic opto-electronic devices, we have investigated the various optical parameters such as absorption coefficient, refractive index, extinction coefficient, reflectivity and dielectric constant of Sn/h-BN heterostructure along with monolayer Stanene and hexagonal Boron Nitride. As a significant finding of the results, a strong redshift has been observed in the absorption coefficient, extinction coefficient and reflectivity, also a strong absorption peak appears in ultra-violet region. The excellent optical properties of heterostructure make it viable for potential optical applications.
原文链接:- NSTL
- Elsevier
Shukla N.Srivastava R.Kaur H.Arora B....
5页查看更多>>摘要：? 2021 Elsevier B.V.Study of long-range interactions is increasingly becoming essential due to its various applications in cold atomic physics. These interactions can be conveniently expressed in terms of various dispersion coefficients. In the present work, theoretical calculations have been carried out for the two-dipole (C6), and three-dipole (C9) dispersion coefficients among the group XII atoms and their ions, viz. Zn, Cd, Hg, Zn+, Cd+, and Hg+. To obtain these coefficients, the dynamic dipole polarizabilities and reduced matrix elements required are evaluated using the relativistic methods. Further, using the calculated matrix elements, the oscillator strengths corresponding to leading transitions and static dipole polarizabilities of these atoms and ions are determined for the comparison purposes.
原文链接:- NSTL
- Elsevier
Garduno-Wilches I.Narro-Rios J.S.Ruiz-Rojas C.A.Aguilar-Frutis M....
5页查看更多>>摘要：? 2021 Elsevier B.V.A CuCrO2/ZnO heterojunction diode was successfully fabricated by ultrasonic spray pyrolysis. The high quality of the layers constituting the diode was determined by XRD, SEM, Ellipsometry, I–V and Impedance spectroscopy measurements, as well as by their optical properties. Backscattered electron microscopy allowed to resolve each layer of the junction. The high density of the films was inferred through the refractive index of the films: 2.02 and 1.97 for the ZnO and the CuCrO2 layers, respectively. I–V measurements showed the characteristic rectification of the diodes, approaching a figure of 107 @ ± 4.5 V. Impedance spectroscopy results showed four different activation energies attributed to the bulk conductivities of CuCrO2 and ZnO, and to the CuCrO2–ZnO and Au–CuCrO2 junctions. The %T of the diode varied from 20% at 400 nm up to 70% at 700 nm, leading to a device that can be classified and used as a semi-transparent diode.
原文链接:- NSTL
- Elsevier
Ghanbari A.Khordad R.Ghaderi-Zefrehei M.
5页查看更多>>摘要：? 2021 Elsevier B.V.The current world observations in COVID-19 are hardly tractable as a whole, making situations of information to be incompleteness. In pandemic era, mathematical modeling helps epidemiological scientists to take informing decisions about pandemic planning and predict the disease behavior in the future. In this work, we proposed a non-extensive entropy-based model on the thermodynamic approach for predicting the dynamics of COVID-19 disease. To do so, the epidemic details were considered into a single and time-dependent coefficients model. Their four constraints, including the existence of a maximum point were determined analytically. The model was worked out to give a log-normal distribution for the spread rate using the Tsallis entropy. The width of the distribution function was characterized by maximizing the rate of entropy production. The model predicted the number of daily cases and daily deaths with a fairly good agreement with the World Health Organization (WHO) reported data for world-wide, Iran and China over 2019-2020-time span. The proposed model in this work can be further calibrated to fit on different complex distribution COVID-19 data over different range of times.
原文链接:- NSTL
- Elsevier
Motawea M.A.Aboelnasr M.A.El-Bahnasawy H.H.Abdel-Khalek E.K....
5页查看更多>>摘要：? 2021 Elsevier B.V.CaFeO3-δ perovskite nanomaterial has been synthesized by sol-gel method. Rietveld analysis of the X-Ray diffraction (XRD) data of the CaFeO3-δ sample revealed orthorhombic perovskite structure (space group pcmn). Field emission scanning electron microscope (FE-SEM) of the CaFeO3-δ sample showed the agglomerations of various particles. M?ssbauer measurement of the CaFeO3-δ sample showed that the value of δ is 0.262 and Fe oxidation states are Fe3+ in octahedral and Fe4+ in tetrahedral coordination. X-ray photoelectron spectroscopy (XPS) revealed that the presence of Fe3+, Fe4+ ions, and oxygen vacancies at the surface of the CaFeO3-δ sample. Thermogravimetry analysis (TG) and differential scanning calorimetric (DSC) of the CaFeO3-δ sample revealed the presence of phase transitions. The magnetic properties of the CaFeO3-δ sample exhibit mainly antiferromagnetic state as confirmed by M?ssbauer measurement. Based on the obtained results, the presence of oxygen vacancies and mixed oxidation states of iron (Fe3+ and Fe4+) makes the CaFeO3-δ sample useful for industrial applications.
原文链接:- NSTL
- Elsevier
Dos Santos L.F.Lima K.O.Gomes L.F.T.Goncalves R.R....
5页查看更多>>摘要：? 2021 Elsevier B.V.Luminescent spherical, redispersable, and monodisperse Er3+,Yb3+ co-doped Y2O3 nanoparticles were synthesized by homogenous precipitation followed by thermal annealing. Cubic Y2O3 nanoparticles exhibited high colloidal stability in water and biological medium and 90% cell viability toward glioblastoma multiforme cell lines. Confocal microscopy revealed cellular internalization of Y2O3 nanoparticles. Upon excitation at 980 nm, efficient near-infrared to visible upconversion luminescence from Y2O3:Er3+,Yb3+ nanoparticles occurred. The upconversion dynamics was determined by the number of photons, which evidenced that energy transfer by the upconversion mechanism is predominated. On the basis of luminescence nanothermometry studies, the nanoparticles exhibited features of a primary thermometer with high thermal sensitivity (1.27 ± 0.05% K?1 (303 K) and large repeatability (>97%), attesting that it can be used as a contactless optical thermal sensor. This primary thermometer is also successfully applied in a cell culture medium showing that the nanoparticles can operate on biological media. This opens the possibility of the use of Y2O3:Er3+,Yb3+ nanoparticles in the design of a theranostic platform, able to simultaneously monitor temperature and, coupled to photosensitizers, produce reactive oxygen species for cancer therapy.
原文链接:- NSTL
- Elsevier
