Narrow Results

The time evolution of the roughness is investigated for one-dimensional systems described by the Kargar–Parisi–Zhang equation. Scaling behavior of the roughness is studied, and the scaling function is obtained.

We develop a simple model of the interface exciton with an electron strongly confined in the interface plane and a hole confined in the quantum well. The main parameters of the theory are: the distance d between the interface plane and center of the quantum well, and the parameters of quantum well (the half-width a and the height V₀). Using the variational method, we obtained the binding energy and effective optical efficiency of this type of interface exciton. This model can be developed to investigate the properties of two-dimensional excitons in coupled quantum well.¹

The generalized two-dimensional Peierls–Nabarro (PN) model⁷ for studying interfaces is developed further, where an exact generalized stacking fault energy γ-surface obtained from ab initio calculations acts as an input function for the generalized PN model. Using the multiscale modeling techniques, which combines elastic theory with ab initio calculations, the structure and energy of the Al/MgO(100) interface are studied, and the effectiveness of this method is demonstrated.

The focus of this study is to experimentally investigate the effect of debonding stress, the interface between the fibers and the polymer matrix, on the damping properties of the short fiberglass reinforced polymer composites. In this study, short fiberglass reinforced polycarbonate composite materials were fabricated and characterized for their tensile properties by varying the fiberglass loading fraction. The debonding stress was evaluated by coupling the acoustic emission technique with the tensile testing. After the determination of the debonding stress was completed, dynamic cyclic testing was performed in order to investigate the effect of debonding on the damping properties of the polymer composites. It was experimentally observed in this study that the debonding can facilitate the stick-slip friction under cyclic loadings, which then gives rise to better damping performance in the fiberglass composites.

Continuous silicon carbide fiber-reinforced silicon carbide (SiC_f/SiC) composites are promising structure candidates for future fusion power systems such as gas coolant fast channels, extreme high temperature reactor and fusion reactors, because of their intrinsic properties such as excellent mechanical properties, high thermal conductivity, good thermal-shock resistance as well as excellent physical and chemical stability in various environments under elevated temperature conditions. In this study, bonding of tungsten and SiC_f/SiC was produced by hot-press method. Microstructure analyses were performed using SEM and TEM.

Co/NM (nonmagnetic Ag and SiO₂)/Co sandwich structure films with different thicknesses of NM were fabricated on Si(111) substrate via oblique radio frequency sputtering. With increasing thickness of nonmagnetic Ag $(t_{\mathrm{\text{Ag}}})$, in-plane magnetic anisotropy field $H_k$ initially increased from 100 Oe of $t_{\mathrm{\text{Ag}}}=0$ nm to 220 Oe of $t_{\mathrm{\text{Ag}}}=1.5$ nm, and then decreased when $t_{\mathrm{\text{Ag}}}>1.5$ nm. Resonance frequency showed the same tendency with maximum 5.2 GHz when $t_{\mathrm{\text{Ag}}}=1.5$ nm. Damp factor increased from 0.02 for $t_{\mathrm{\text{Ag}}}=0\text{–}0.08$ for $t_{\mathrm{\text{Ag}}}=2.0$ nm. The same result was observed in inserting oxide nonmagnetic SiO₂ layer. This can be attributed to the competition between interface energy and exchange coupling energy.

We analyze the localization in three-layered symmetric structure consisting of linear layer between focusing nonlinear media separated by nonlinear interfaces. The mathematical formulation of the model is a one-dimensional boundary value problem for the nonlinear Schrödinger equation. We find nonlinear localized states of two types of symmetry. We derive the energies of obtained stationary states in explicit form. We obtain the localization energies as exact solutions of dispersion equations choosing the amplitude of the interface oscillations as a free parameter. We analyze the conditions of their existence depending on the combination of signs of interface parameters.

We describe the non-symmetrical spatial-distributed electric field near the thin optic layer with nonlinear properties that separated two focusing and defocusing media with Kerr-type nonlinearity differing by values of refractive index. The nonlinear Schrödinger equation (NLSE) with nonlinear potential containing two parameters describes the distribution of electric field strength in adiabatic approximation. The problem is reduced to the solution of NLSEs at the half-spaces with the nonlinear boundary conditions at the interface plane. We obtain five new types of nonlinear stationary states describing the confinement effect of electric field strength across the interface. The field confinement effect is the localization of nonlinear spatially periodic wave during the transition from a one half-space to another one where the field distribution is monotonically damping from the interface. We derive and analyze the frequencies of field confinement effect possibility in dependence of media and interface characteristics.

This paper presents a sigma-delta interface for fluxgate sensor based on a single-loop high-order modulation. A feedforward summation loop structure can reduce the linearity overload in integrators and the swing of integration signals. A Local feedback branch is proposed to realize the zero of noise transfer function (NTF) optimization and enhance noise shaping performance within signal band. The interface is fabricated in a standard 0.5 $\mu$m CMOS process and the active circuit area is about 13 mm². The chip consumes 120 mW from a 10 V supply with a sampling clock of 250 k Hz. The average noise floor of the digital fluxgate is about −115 dBV/Hz${}^{1/2}$ over a 100 Hz bandwidth.

In this paper, we study the effect of the axial deformation of carbon nanotubes in the zigzag and armchair directions on the stability of the interface between hydrogenated and non-hydrogenated regions. We analyze the specific energy of this interface as a function of the axial strain. We found that the clear interface can be obtained at a wider temperature range due to tube stretching. The energy barriers characterizing the process of hydrogen migration from the hydrogenated region of the nanotube to the pristine tube are calculated. It is concluded that the tube deformation significantly affects the stability of the system. For some tubes applied strain can qualitatively change the regularity of hydrogenation, changing the sign of the interface energy.

The excellent photoelectric properties and low fabrication cost of perovskite solar cells have attracted extensive research attention. Despite this, long-term stability issues associated with perovskite solar cells continue to pose a significant barrier to commercialization. A new generation of two-dimensional (2D) and quasi-2D perovskites and newly introduced members of the 2D material family, have attracted growing attention due to their excellent stability and physical properties in contrast to their three-dimensional (3D) counterparts. Herein, we have presented the feasibility of using 4,$4^{\prime }$-dipyridyl as an additive material for quasi-2D perovskite solar cells. As a result of the addition of 4,$4^{\prime }$-dipyridyl, the solar cell device achieves a power conversion efficiency of 17.92% and a fill factor of 76.5%. Additionally, this strategy can be expanded to quasi-2D perovskite solar cells with an open-circuit voltage of 1.05V.

In this paper, the effects of rare earth elements on the bonding strength and stability of TiC/fcc-Fe interface are explored by using the first-principles method based on density functional theory. The results show that the Ti terminal is more stable than the C terminal in the process of forming the interface. The alloying elements tend to segregate at position 2 on the side of fcc-Fe. The segregation of Mo, Nb, Cr and Ce alloying elements increases the interatomic electron cloud enrichment and consumption between the interfaces and enhances the Fe–Ti interactions. The d orbitals of Mo, Nb, Cr and Ce and f orbitals of Ce have strong hybridization with Fe-d orbitals and Ti-d orbitals electrons near the Fermi energy level, indicating an increase in bonding strength and stability of the interfaces. When Fe atoms are replaced by W, Ni and Al atoms, the covalent bond strength between interfacial atoms is reduced, thus weakening the interfacial bonding strength. This provides solid theoretical foundation with regard to further application in austenitic heat-resistant steel fields.

In this study, molecular dynamics simulations were employed to investigate the effect of symmetrical tilt grain boundaries (STGBs) on the cascade collision evolution at the SiC/PyC interface. We observed that the tilt angle size of grain boundary (GB) spatial structures significantly influences both the type and number of defects caused by primary knock-on atom (PKA) collisions at the interface, altering the cascade damage morphology. Under the PKA range from 1.5keV to 15keV at 1000K, the interplay between GB and interface damage throughout various cascade collision stages impacts defect generation and PKA efficiency. Integrating the analyses of displacement cascade morphology, threshold displacement energy (TDE), and Frenkel pairs (FPs) evolution, it is evident that GBs introduced into the SiC/PyC interface with single crystals exhibit reduced defect absorption efficiency. This implies the existence of competing mechanisms of GB damage and interfacial damage. Notably, the GB plane near the interface exhibits enhanced irradiation resistance and atomic arrangement stability compared to areas without GB. Overall, our results offer crucial insights into the irradiation resistance mechanics of ceramic composite interfaces, laying the groundwork for future studies.

The model of the composite symmetric waveguide consisting of self-focusing slab between defocusing nonlinear media separated by interfaces characterized by own nonlinearity response is proposed. Two new types of nonlinear surface waves propagating along it with anti-phase amplitude oscillations at interface planes are found. The frequencies of the nonlinear surface waves existing near the interfaces with the nonlinear response only are calculated analytically. The conditions of the surface wave existence are found. The frequencies and localization distances of the surface waves in dependence on nonlinearity waveguide parameters, slab width and interface characteristics are analyzed.

The nonlinear surface waves propagating along the ultra-thin-film layers with nonlinear properties separating three nonlinear media layers are considered. The model based on a stationary nonlinear Schrödinger equation with a nonlinear potential modeling the interaction of a wave with the interface in a short-range approximation is proposed. We concentrated on effects induced by the difference of characteristics of the layers and their two interfaces. The surface waves of three types exist in the system considered. The dispersion relations determining the dependence of surface waves energy on interface intensities and medium layer characteristics are obtained and analyzed. The localization energy is calculated in explicit form for many difference cases. The conditions of the wave localization on dependence of the layer and interface characteristics are derived. The surface waves with definite energies in specific cases existing only in the presence of the interface nonlinear response are found. All results are obtained in an explicit analytical form.

The interface behavior may significantly influence the mechanical properties of carbon nanotube (CNT)-reinforced composites due to the large interface area per unit volume at the composite. The modeling of CNT/polymer interfaces has been a challenge in the continuum modeling of CNT-reinforced composites. This paper presents a review of recent progress to model the CNT/matrix interfaces via a cohesive law established from the van der Waals force. A simple, analytical cohesive law is obtained from the inter-atomic potential, and is used to study the effect of CNT/matrix interfaces on the macroscopic properties of CNT-reinforced composites.

To reveal the wear mechanism of hyperbranched polysilane (HBPSi) grafted multi-walled carbon nanotubes (HBPSi–MWCNTs) modified benzoxazine–bismaleimide (BOZ–BMI) resin (HBPSi–MWCNTs/BOZ–BMI), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were employed. The results indicated that the suitable addition of HBPSi–MWCNTs could largely enhance the tribological properties of BOZ–BMI composites. The worn surface of the composites showed that the severe wear of the BOZ–BMI resin was converted from adhesive wear to abrasive wear with the addition of HBPSi–MWCNTs. The excellent tribological properties can be attributed to the improved interfacial adhesion between HBPSi–MWCNTs and the BOZ–BMI resin matrix. The TGA demonstrated that the composite with 0.8wt.% HBPSi–MWCNTs exhibits better thermal resistance; thus, it can inhibit adhesive wear during the friction process. The XPS spectra and the surface energy showed that the HBPSi–MWCNTs could be exposed on the worn surface of the composite to improve the anti-wear capacity of the composites further.

Defects and stress distribution in the interface of Ge/Si hetero-structures play an important role in silicon-based semiconductor devices. This work at atomic scale performs molecular dynamics simulations to study the packing characteristics in the Ge/Si interface and loading features on the atoms for different contacting configurations between Ge nanopillars and Si substrates. Based on the analysis of energy, composition, the distribution of hydrostatic pressure, the Lode–Nadai parameters of each atom as well as visualized atomic packing images in the interface regions, simulation results show that contacting configurations of the Ge nanopillar with the (100) surface and the (110) surface of the Si substrate significantly affect the stability of the interface structures. The load-bearing positions of the Si surface and the inter-diffusion among the atoms in the interface regions greatly contribute to the lattice distortion of the silicon substrate, the composition, defects, and local stress distribution in the interface regions.

The dynamic propagation of a crack in a functionally graded piezoelectric material (FGPM) interface layer between two dissimilar piezoelectric layers under anti-plane shear is analyzed using the integral transform approaches. The properties of the FGPM layers vary continuously along the thickness. FGPM layer and the two homogeneous piezoelectric layers are connected weak-discontinuously. A constant velocity Yoffe-type moving crack is considered. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM. Followings are helpful to increase of the resistance of the crack propagation of the FGPM interface layer: (a) certain direction and magnitude of the electric loading; (b) increase of the thickness of the FGPM interface layer; (c) increase of the thickness of the homogeneous piezoelectric layer which has larger material properties than those of the crack plane in the FGPM interface layer. The DERR always increases with the increase of crack moving velocity and the gradient of the material properties.

Intraband transitions of an impurity electron from the ground state to 2P_x and 2P_y excited states of a shallow donor located near a semiconductor-metal interface are investigated as a function of the donor distance from the interface. Impurity states are calculated within the effective mass approximation and using a variational scheme in which the energies and the oscillator strength for the intraband absorption are obtained analytically.