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We study the effects of an applied magnetic field on mobile charges in a composite beam of piezoelectric semiconductor and piezomagnetic layers. The macroscopic theory of piezoelectrics/piezomagnetics and the drift–diffusion theory of semiconductors are used. A one-dimensional model for beam bending is derived. An analytical solution is obtained, showing that bending and axial polarization develops in the beam under the applied magnetic field and that the mobile charges move to screen the effective polarization charges. Hence the composite beam exhibits an interaction between the applied magnetic field and semiconduction. The results are useful in piezotronic devices interacting with magnetic fields.

This work investigates the dispersion properties of Rayleigh-type surface waves propagating in a layered piezoelectric nanostructure composed of a piezoelectric nanofilm over an elastic substrate. As one of the most important features of nanostructures, surface effects characterized by surface stresses and surface electric displacements are taken into account through the surface piezoelectricity theory and the nonclassical mechanical and electrical boundary conditions. Concrete expressions of the dispersion equation are derived, and numerical results are provided to examine the effects of several surface-related parameters, including the surface elasticity, surface piezoelectricity, surface dielectricity, surface density, as well as surface residual stress, on the dispersion modes and phase velocity. The size-dependent dispersion behaviors occurring with surface effects are also predicted, and they may vanish once the thickness of the piezoelectric nanofilm reaches a critical value.

This paper theoretically studies the axisymmetric frictionless indentation of a transversely isotropic piezoelectric semiconductor (PSC) half-space subject to a rigid flat-ended cylindrical indenter. The contact area and other surface of the PSC half-space are assumed to be electrically insulating. By the Hankel integral transformation, the problem is reduced to the Fredholm integral equation of the second kind. This equation is solved numerically to obtain the indentation behaviors of the PSC half-space, mainly including the indentation force-depth relation and the electric potential-depth relation. The results show that the effect of the semiconductor property on the indentation responses is limited within a certain range of variation of the steady carrier concentration. The dependence of indentation behavior on material properties is also analyzed by two different kinds of PSCs. Finite element simulations are conducted to verify the results calculated by the integral equation technique, and good agreement is demonstrated.

This work aims to provide a fundamental understanding on the dispersive behaviors of shear horizontal (SH) surface waves propagating in a layered piezoelectric nanostructure consisting of an elastic substrate and a piezoelectric nanofilm by considering the surface effects. Theoretical derivation based on the surface piezoelectricity model was conducted for this purpose, and analytic expressions of the dispersion equation under the nonclassical mechanical and electrical boundary conditions were obtained. Numerical solutions were given to investigate the influencing mechanism of surface elasticity, surface piezoelectricity, surface dielectricity, as well as the surface density upon the propagation characteristics of SH surface waves, respectively. The results also reveal the size-dependence of dispersive behaviors, which indicates that the surface effects make a difference only when the thickness of the piezoelectric nanofilm stays in a certain range.

Two-dimensional/three-dimensional (2D/3D) hierarchical structure has attracted extensively attention in recent years due to their stability and the enhanced open-circuit voltage of perovskite solar cells. However, the solution processed thin 2D perovskite layers on the surface of 3D perovskites would lead to undesirable intermixing between the two phases, impeded carrier transport. Here, we present a novel approach for fabricating 2D perovskite on 3D perovskite using vapor-assisted solution deposition. Unlike what is normally observed in solution-processed 3D/2D systems, a flat interface formed in the 2D/3D bilayer heterostructure. The vapor-deposited 2D perovskite capping layer promotes efficient electron and hole separation processes and significantly restrain non-radiative charge recombination. This innovative stable and low-cost architecture will enable the timely commercialization of perovskite solar cells.

The dolomite of the fourth member of Dengying Formation in Gaoshiti-Moxi area of central Sichuan Basin is rich in hydrocarbon resources. It has experienced superimposition-reformation of multistage karstification, and is the key target for studying deep ancient carbonate reservoirs. Exploration and development practices show that there are great differences in the development of karst reservoirs of the fourth member of Dengying Formation between the platform margin and intraplatform in Gaoshiti-Moxi area. However, the differences in the genetic mechanism of karst reservoirs between these two zones are unclear. Therefore, based on an integrated analysis of core, thin section, drilling, logging, and geochemical test data, this study clarifies the differences in karstification between the platform margin and intraplatform and conducts a comparative analysis of the controlling factors for the differences in karst reservoirs. Results show that the fourth member of Dengying Formation experienced superimposition-reformation of four types of paleokarstification, including eogenetic meteoric water karst, supergene karst, coastal mixed water karst, and burial karst. Large-scale dissolved fractures and caves are mainly controlled by meteoric water karstification, primarily developing three types of reservoir space: vug type, fracture-vug type, and cave type. Dolomite and quartz fillings are mainly formed in the medium-deep burial period. Four types of paleokarstification are developed in the platform margin, while the coastal mixed water karst is not developed in the intraplatform. Eogenetic meteoric water karst and supergene karst in the platform margin are stronger than those in the intraplatform, while burial karst shows no notable difference between the two zones. The thickness of soluble rock (mound-shoal complex), karst paleogeomorphology, and different types of paleokarstification are the main controlling factors for the difference in karst reservoirs between the platform margin and the intraplatform.

Hypogene karst is a special manifestation of karst development in spatial scale. Intensive study of its development mechanism has significant meaning for engineering construction, shale gas and geothermal exploitation. To reveal the developing pattern of hypogene karst in Huanjiang syncline, karst groundwater at different depths in wells HD1-2 and HD1-4 and karst springs was selected as the research object. Through the analysis of geochemistry and stable isotopes of karst groundwater, it was revealed that the circulation pattern of deep karst water came from the common recharge of meteoric water and fossil water hosted in karst caves, runoff of deep faulting belts and discharge of large karst springs, over Huanjiang syncline, which provides good hydrodynamic conditions for hypogene karst development. Meanwhile, the widely developed faulting belts and structural fissures provide primitive dissolution space. Through the above analysis, the paper constructs a hypogene karst development pattern controlled by the deep cycle of groundwater in Huanjiang syncline.

The thickness-shear and thickness-twist vibrations of a finite and partially electroded AT-cut quartz resonator are investigated. The equations of anisotropic elasticity are used with the omission of the small elastic constant c56. An analytical solution is obtained using Fourier series from which the free vibration resonant frequencies, mode shapes, and energy trapping are calculated and examined.

In this paper, Love waves propagating in a piezoelectric semiconductor (PSC) layered structure are investigated, where a PSC thin film is perfectly bonded on an elastic dielectric half-space. The dispersion equations are derived analytically. The influence of semiconducting properties on the propagation characteristics is examined in detail. Numerical results show that the semiconducting effect reduces the propagation speed, and that the Love waves can propagate with a speed slightly higher than the shear wave speed of the elastic dielectric half-space. The wave speed and attenuation significantly depend on the steady-state carrier density and the thickness of the PSC thin film. It is also found that when the horizontal biasing electric field is larger than the critical value (corresponding to the zero attenuation), the wave amplitude is increased. These findings are useful for the analysis and design of various surface wave devices made of PSC.

This paper deals with the propagation of bending waves along the free edge of a piezoelectric sandwich plate. The structure consists of a piezoelectric layer sandwiched between two metal layers. The first-order Zig-Zag approximation for in-plane displacements through the thickness of each layer is used. Interfacial continuity of the displacement and the transverse shear stress between the piezoelectric layer and the metal layer is ensured which is very important and also experienced by layered structures. The number of independent unknown variables is reduced from 14 to 4 by using the interfacial continuity and the zero shear stresses conditions at the top and bottom surfaces. The governing equations and corresponding boundary conditions are derived using Hamiltonian principle. The dispersion relations for electrically open and shorted boundary conditions imposed at the edge of the semi-infinite piezoelectric sandwich plate are obtained. The effects of electrical edge condition, layer thickness ratio and material property on dispersion characteristics of the localized bending waves are discussed. The numerical results show that the electrical edge condition has significant influence on dispersion property compared to edge wave in a piezoelectric single-layer plate. The phase velocity and the localization of bending edge wave significantly depend on the thickness of metal layer, and a thick metal layer can result in a high wave velocity and a strong localization. The phase velocity of bending wave is positively related to the velocities of classical Rayleigh surface wave in piezoelectric half-space and metal half-space under plane strain.