Modern Physics Letters B

Excellent semiconductors and novel optical properties are the first criteria for nanomaterial technology. In this paper, the S-atom defect is applied to 1T-NbS₂ for the first time, and doping atoms are introduced. The concentration of doping atoms is 3.84% and 4% under the two types of defects. Finally, the metallic properties of NbS₂ were weakened successfully, and the highest indirect band gap of 0.27eV was induced, which gradually transformed into a brand-new semiconductor material. In addition, partially composite systems exhibit excellent electromagnetic storage, polarizability, and infrared light absorption, showing high reflectivity in the visible and low-frequency UV regions, which can be used to make blackout lenses and reflective coatings. Cd composite systems can be used as a new type of conducting semiconductor for all kinds of equipment.

Recent huge progress in the field of chemical doping for modifying the physical properties of nano-materials has inspired us to perform this investigation on the electronic and optical properties of GeSe/SnSe vertical heterojunction via P-doping. The calculated results indicate that the pristine GeSe/SnSe vertical heterojunction is a semiconductor and shows a type-II band alignment. After P-doping, all doped heterojunctions have good structural stability due to the negative binding energies. Interestingly, the typical p-type and n-type degenerate semiconductors can be found. In addition, the optical properties including the absorption coefficient, reflectivity and loss function of P-doped GeSe/SnSe vertical heterojunction are discussed. Particularly, in the ultraviolet light range, the optical absorption coefficient of P-doped systems can reach up to $14\times 10^5$cm${}^{-1}$, which suggests that P-doping GeSe/SnSe vertical heterojunctions can serve as a promising material for ultraviolet light detecting. Meanwhile, the absorption and the loss peaks of doped cases exhibit an apparent trend of blue shift with respect to the pristine heterojunction. All these interesting results show that the P-doping gives GeSe/SnSe heterojunction the possibility to tune its electronic and optical properties.

In this paper, we study the decaying dynamics in the mirror-field interaction by means of the intrinsic decoherence scheme. Factorization of the mirror-field Hamiltonian with the use of displacement operators allows us to calculate the explicit solution to Milburn’s equation for arbitrary initial conditions. We show expectation values, correlations, and Husimi functions for the solutions obtained.

This paper presents the elastic deformation and thermodynamic theory for crystals with HCP structure on the basis of the statistical moment method (SMM) together with numerical results and discussions for metals Mg, Zn, Dy, Er and Gd. Some numerical results are compared with experiments and other calculations.

The intent of this work to implement first-integral method to study traveling wave solutions of some space-time nonlinear fractional differential equations (FDEs) and present their graphical simulations for analyzing different wave profiles. We show how a specific properties of Gamma functions and wave transformation can be used to reduce a FDE to an ordinary one. This method works well and reveals distinct exact solutions which are classified into two different types, namely trigonometric function and hyperbolic function solutions. The results are also depicted graphically in both 3D and 2D for different values of associated parameters. The obtained results may be useful to understand ion-acoustic waves in plasma, shallow water waves in seas and the evolution of a wave packet in three dimensions with finite depth on water under weak nonlinearity by the space-time-fractional regularized long wave equation and space-time-fractional Davey–Stewartson equation, respectively.

The multitudinous expressions of the heat capacity possibly and impossibly appearing in ultra-low temperature thermodynamic systems are determined by using the Nernst theorem. It is found that the expression of the heat capacity possibly appearing in ultra-low temperature systems must satisfy Nernst’s theorem. Crucially, control discrimination methods are presented mathematically through which it can be judged for one new expression of the heat capacity that it possibly appears in ultra-low temperature thermodynamic systems or is fictional. These findings will contribute to enhancing our understanding of the behavior of ultra-low temperature systems.

In this paper, the effects of the thermostability, band structure, and the external electric field on the electronic structure of MoSe₂/Arsenene heterojunction are calculated based on the density functional theory. The calculation results show that the MoSe₂/Arsenene heterojunction is a type-II heterojunction with a bandgap of 0.89eV. When MoSe₂ and arsenene combine by van der Waals force, the electrons are transferred from MoSe₂ to arsenene, the holes are transferred from arsenene to MoSe₂, with the direction of the internal electric field from MoSe₂ to arsenene. The MoSe₂/Arsenene heterojunction with valence band top and conduction band bottom contributed by arsenene and MoSe₂, respectively, shows excellent thermostability at room temperature. The external electric field can effectively modulate the electronic structure of heterojunction. When the electric field is negative, electrons are transferred from MoSe₂ to arsenene and holes from arsenene to MoSe₂. The Fermi level of arsenene moves down while that of MoSe₂ moves up. When the electric field is positive, the direction of electron and hole transfer are opposite to that when the electric field is negative. The Fermi energy level of arsenene and MoSe₂ also move in the opposite direction.

The heat transfer and oxygen transport behaviors of Ti-6Al and Fe-12Cr alloys directly affect their aeronautical material application. In order to investigate the flame retardant mechanism in atomic scale, molecular dynamic (MD) simulations were performed to study the heat transfer and oxygen transport performances of Ti-6Al and Fe-12Cr alloys in the linear and uniform heating treatment. Next, the ignition performances of Ti-6Al and Fe-12Cr alloys were further verified by the frictional ignition tests. Therefore, this is a multi-scale research with a novel combination of MD simulations and ignition tests. Those obtained results show that the heat is more concentrated at the heating edge of Ti-6Al alloy while at the same heating rate. This leads to the intensification of atomic motion at the heating edge, and reduces the structural thermal stability of Ti-6Al alloy’s heating edge. Therefore, the heat transfer performance of Fe-12Cr alloy at the same state is better than that of Ti-6Al alloy. When there is an oxide layer on the surface of these two alloys, Fe-12Cr alloy can inhibit the oxygen transfer more effectively than Ti-6Al alloy, and further improve its flame retardant property. In addition, the frictional ignition tests with Ti alloy rotor under the same airflow environment show that the critical airflow velocity of the Fe-12Cr alloy stator is about 114m/s higher than that of Ti-6Al-4V alloy stator at 384^∘. Generally, according to MD simulations and frictional ignition tests, it could be concluded that the flame retardancy of Fe-12Cr alloy is higher than Ti-6Al alloy.

The utilization of a new category of nanofluids, termed hybrid nanofluid, has recently been adopted to elevate the heat transfer rate. This research aims to analyze the significance of thermal radiative flux and entropy generation on the flow of hybrid nanofluid within a vertical channel. Specifically, the Al₂O₃–TiO₂/CMC-water hybrid nanofluid is assumed to be produced by suspending hybrid nanoparticles of alumina (Al₂O₃) and titanium oxide (TiO₂) in CMC-water (0.0–0.4%). The equations governing the problem are converted into a set of ordinary differential equations by utilizing appropriate similarity conversions, which are then solved through the Homotopy Analysis Method (HAM). The Brinkman number’s significant influence on the Bejan number and the regulation of entropy in the system is discovered. The results of the skin friction coefficient, heat transfer rate, entropy generation, and Bejan number are depicted through graphical representation, covering a wide range of parameter values.

Periodic nanostructure is a novel method to manipulate the electronic properties in electronics. An efficient method in this paper is proposed to judge whether m identical periods’ magnetic nanostructure is a periodic structure by judging whether its physical structure and its magnetic vector potential structure both keep periodic. By investigating the influence of the $\delta$-doping potential on the electron transport properties with m identical periods’ magnetic barrier nanostructure of InAs system, it shows that, firstly, the resonant peak of transmission probability, conductance, and spin polarization has been induced by splitting into (2$m-1$) folds with m units nanostructure, respectively, especially when the resonant peak of transmission probability is almost close to 1 as the incident energy is lower; secondly, the height of $\delta$-doping potential has an extensive influence on the resonant peak of transmission probability, which the resonant peak will be more dependent of the height of $\delta$-doping potential increasing. Meanwhile, the conductance will be decreased with the height of $\delta$-doping potential increasing.

In this paper, the effects of transition metal doping on the electronic structure of monolayer NbS₂ were studied through the first principles. The electronic structure changes caused by doping transition metal (TM) atoms were recorded, including the energy band, the density of states, binding energy, and optical properties. Studies show that all doping systems are metal. Still, under strain regulation, some doping systems offer an indirect bandgap; NbS₂ transforms into a narrow bandgap diluted semiconductor and can improve the activity. Doping atoms lead to $n(p)$ type doping in NbS₂.

Regarding optical properties, IVB group metals are selected as the typical dopant of three periods. Composite NbS₂ has excellent reflector characteristics and can be applied to infrared and ultraviolet regions. The spectral response and electromagnetic wave absorption range of low-energy areas are also improved. This study effectively solves the problem of impurity states introduced by doping and provides a solution for the doping modification of monolayer NbS₂, which will lay a foundation for nanoelectronics.

The transport properties of gold clusters with eight and nine atoms between gold electrodes are investigated by using non-equilibrium Green’s function method combined with density functional theory. Negative differential resistance effect is found both in Au₈ and Au₉. From a new respect, the mechanism for the negative differential resistance effect is explored through calculating the number of electrons of the atoms in the clusters at different bias voltages. When Au₉ takes vertical orientation, it is found that the voltage can change the coupling strength of the sandwiched system. When the value of the voltage is small, the current increases with decreasing of the cluster-electrode separation. But when the voltage increases to a certain value, the current decreases with decreasing of the cluster-electrode separation. When Au₉ takes parallel orientation, different from other electronic transport systems, it is found that the transport behaviors for Au₉ are not sensitive to the cluster-electrode separation, showing that this configuration has a better transport stability over the changes in distance, which may provide some new clues for developing future electron device.