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1.
In this paper, we classify static spherically symmetric (SS) perfect fluid space-times via conformal vector fields (CVFs) in f(T) gravity. For this analysis, we first explore static SS solutions by solving the Einstein field equations in f(T) gravity. Secondly, we implement a direct integration technique to classify the resulting solutions. During the classification, there arose 20 cases. Studying each case thoroughly, we came to know that in three cases the space-times under consideration admit proper CVFs in f(T) gravity. In one case, the space-time admits proper homothetic vector fields, whereas in the remaining 16 cases either the space-times become conformally flat or they admit Killing vector fields.  相似文献   
2.
Methods capable of tuning the properties of van der Waals (vdW) layered materials in a controlled and reversible manner are highly desirable. Interfacial electronic properties of two-dimensional vdW heterostructure consisting of silicene and indium selenide (InSe) have been calculated using density functional theory-based computational code. Furthermore, in order to vary the aforementioned properties, silicene is slid over a InSe layer in the presence of Li intercalation. On intercalation of the heterostructure, the buckling parameter associated with the corrugation of silicene decreases from 0.44 Å to 0.36 Å, whereas the InSe structure remains unaffected. Potential energy scans reveal a significant increase in the sliding energy barrier for the case of intercalated heterostructure as compared with the unintercalated heterostructure. The sliding of the silicene encounters the maximum energy barrier of 0.14 eV. Anisotropic analysis shows the noteworthy differences between calculated in-plane and out-of-plane part of dielectric function. A variation of the planar average charge density difference, dipole charge transfer and dipole moment have been discussed to elucidate the usability spectrum of the heterostructure. The employed approach based on intercalation and layer sliding can be effectively utilized for obtaining next-generation multifunctional devices.  相似文献   
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An increasing trend toward integration of polymers in microelectronics and organic electronics has recently boosted research focusing in metal-polymer interfaces. These two materials differ vastly, with the former forming dense, crystalline, cohesive structures and the latter forming open structures bound together by weak van der Waals forces. As a result, there is dire need to assess their surface features (e.g., roughness) and correlate them with corresponding growth parameters, as metal-polymer interfaces are mainly determined by the preparation process. Here, we report a laboratory-based grazing-incidence small-angle x-ray scattering (GISAXS) study on distinct gold-polymer interfaces fabricated with different growth mechanisms, utilizing in-plane and oblique sputter geometries. GISAXS provided an improved analytic scheme for the buried surface in free-standing 2D gold-polymer nanosheets (with 19% porosity) revealing their fractal structure (Porod slope: ?1.71). Two quantitative approaches (Height-Height Correlation and Power Spectral Density functions) were used to describe rough surfaces characterized by Atomic Force Microscopy (AFM) in consort with GISAXS data; different correlation length dependencies on growth time were revealed for gold rough surfaces grown on bare and polymerized Si. The results are considered pertinent to interfacial nanoscience and engineering, enabling statistical data collection from large surface areas, in a fast and nondestructive manner.  相似文献   
6.
The dispersion relations and Landau damping of Alfven waves in kinetic and inertial limits are studied in temperature anisotropic Cairns distributed plasma.In the case of kinetic Alfven waves(KAWs),it is found that the real frequency is enhanced when either the electron perpendicular temperature or the non-thermal parameter A increases.For inertial Alfven waves(IAWs),the real frequency is slightly affected by the electron temperature anisotropy and A.Besides the real frequency,the damping rate of KAWs is reduced when the electron perpendicular temperature or A increases.In the case of IAWs,the temperature anisotropy and A either enhance or reduce the damping rate depending upon the perpendicular wavelength.These results may be helpful to understand the dynamics of KAWs and IAWs in space plasmas where the non-Maxwellian distribution of particles are routinely observed.  相似文献   
7.
Highly spin-polarized ferromagnetic materials are essential for efficient spintronic devices. Here, 100% spin-polarized compounds Rb2TaZ6 (Z = Cl, Br) studied via density functional theory are reported. These compounds show stability in the ferromagnetic phase with cubic symmetry and half metallic behavior, thereby exhibiting a nonzero direct band gap in the spin-down channel and zero band gap in the spin-up configuration. The Ta-d sates contribute mainly to the net magnetic moments as explained by the crystal field theory and density of states. High Curie temperatures of 960.35 and 1021.74 K for Ra2TaCl6 and Rb2TaBr6, along with maximum spin polarizability, make these compounds favorable for efficient spintronic applications.  相似文献   
8.
Hydrogen can be utilized as an energy source; therefore, hydrogen storage has received the most appealing examination interest in recent years. The investigations of hydrogen storage applications center fundamentally around the examination of hydrogen capacity abilities of recently presented compounds. XSrH3 (X = K and Rb) compounds have been examined by density functional theory (DFT) calculations to uncover their different characteristics, as well as hydrogen capacity properties, for the first time. Studied compounds are optimized in the cubic phase, and optimized lattice constants are obtained as 4.77 and 4.99 Å for KSrH3 and RbSrH3, respectively. These hydrides have shown negative values of formation enthalpies as they are stable thermodynamically. XSrH3 might be used in hydrogen storage applications because of high gravimetric hydrogen storage densities, which are 2.33 and 1.71 wt% for KSrH3 and RbSrH3, respectively. Moreover, electronic properties confirm the semiconductor nature of these compounds having indirect band gaps of values 1.41 and 1.23 eV for KSrH3 and RbSrH3, respectively. In addition, mechanical properties from elastic constants such as Young modulus and Pugh's ratio, also have been investigated, and these compounds were found to satisfy born stability conditions. Furthermore, Pugh's ratio and Cauchy pressure show that these hydrides have a brittle nature. Furthermore, thermodynamic properties such as entropy and Debye temperature have been examined using the quasiharmonic Debye model for different temperatures and pressures.  相似文献   
9.
Synthesis of nanomaterials is being gained extensive attention in the fields of chemistry, applied physics, catalysis, drug delivery and the most important in diagnosis and therapeutic applications. Recently, many reports have been published on physical and chemical synthesis of magnetic as well as metallic nanoparticles (NPs) with viable surface functionalization, but still there is a dire need of such strategies that can combine synthetic methodology with stable surface modification found in nature. Synthesis of NPs via biological methods is the possible way to solve these barriers. However, systematized summary and outlooks of NPs synthesis via biological entities with various influencing factors e.g. temperature, pH, concentration of reactants and reaction time has rarely been reported. This review will present the distinct advantages of biological synthesis of NPs over physical and chemical methods. It will also highlight the recent progress on synthesis of NPs via various biological systems i.e. plant, fungus, bacteria, and yeast. Furthermore, it will explain various factors that control the size, shape, and morphology of these NPs. Finally, it would present the future perspectives of green chemistry for the development of nano-science and -biotechnology.  相似文献   
10.
The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg_2X_2(X = N,P,As,Sb,Bi).A full potential linearized augmented plane wave plus local orbitals method is used along with different exchange–correlation potentials to obtain the lattice constants,phonons,electronic,and optical properties of the Sr Mg_2X_2(X = N,P,As,Sb,Bi) Zintl compounds.A good agreement is achieved and our calculations are validated by previous experimental and theoretical data.All compounds have shown stable dynamical behavior with gamma centered longitudinal response having no imaginary frequencies.Electronic band structures reveal the semiconducting nature of the compounds.The Pnictogen(X)-p state contributed mainly in the valence band and the Sr-d state forms the conduction of the compounds.Relative charge transfer and low overlapping of the atomic densities indicates the preferable ionic bonding character of these materials.In the optical properties,real and imaginary parts of dielectric function,complex refractive index,birefringence,reflectivity,and optical conductivity are calculated.These compounds can be utilized in the optical and optoelectronic devices.  相似文献   
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