In this paper,the dispersion,attenuation,and bandgap characteristics of in-plane coupled Bloch waves in one-dimensional piezoelectric semiconductor(PSC)phononic crystals are investigated,emphasizing the influence of p...In this paper,the dispersion,attenuation,and bandgap characteristics of in-plane coupled Bloch waves in one-dimensional piezoelectric semiconductor(PSC)phononic crystals are investigated,emphasizing the influence of positive-negative(PN)junctions.Unlike piezoelectric phononic crystals,the coupled Bloch waves in PSC phononic crystals are attenuated due to their semiconductor properties,and thus the solution of Bloch waves becomes more complicated.The transfer matrix of the phononic crystal unit cell is obtained using the state transfer equation.By applying the Bloch theorem for periodic structures,the dispersion relation of the coupled Bloch waves is derived,and the dispersion,attenuation,and bandgap are obtained in the complex wave number domain.It is found that the influence of the PN junction cannot be neglected.Moreover,the effects of the PN junction under different apparent wave numbers and steady-state carrier concentrations are provided.This indicates the feasibility of adjusting the propagation characteristics of Bloch waves through the regulation of the PN heterojunction.展开更多
This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylin...This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylinder structure.This PS concentric cylinder structure is composed of three regions:an inner PS cylinder,an outer PS cylindrical shell,and a cylindrical PN junction at the interface between the two aforementioned regions.First,the basic equations of the PS concentric cylinder structure are derived,taking into account the coupling of the mechanical displacement,electric potential,and charge carrier perturbation in the cylindrical coordinate system.Next,a mathematical model for the SCWs in this PS concentric cylinder structure is established,utilizing the spectral method and considering the physical characteristics of the cylindrical PN junction.Finally,the dispersion and attenuation curves of the SCWs are numerically calculated to discuss the influence of the interface effect resulting from the cylindrical PN junction.It is found that the existence of a cylindrical PN junction can either reduce or enhance the mechanical-to-electrical energy conversion,which is closely related to the doping mode,doping concentration,and curvature radius of the cylindrical interface.A reasonable design of the aforementioned parameters can optimize the wave motion in acoustic equipment formed by PS media with different frequencies or wavelengths.The construction and resolution of the mathematical model as well as the analysis of physical mechanisms can offer theoretical guidance for improving the efficiency of energy conversion from mechanical energy to electrical energy and optimizing the acoustic performance of energy harvesting devices.展开更多
The Lower Member of the Longrnaxi Forma-tion is generally dominated by siliceous shale,but recently we found some siltstone-mudstone rhythm sections developed in the Lower Member of the Longmaxi Formation.The study of...The Lower Member of the Longrnaxi Forma-tion is generally dominated by siliceous shale,but recently we found some siltstone-mudstone rhythm sections developed in the Lower Member of the Longmaxi Formation.The study of formation mechanism of siltstone-mudstone rhythmic sedimentary sections may provide new insights into the shale sedimentary environ-ment.Therefore,we studied the characteristics and formation mechanism of siltstone-mudstone rhythmic sedimentary sections in the Lower Member of the Long-maxi Formation in the Changning area based on core observation,thin section identification,major elements and trace elements analysis.The results show the following:1)Two siltstone-mudstone rhythmic sedimentary sections are characterized by frequent interbed between black or gray-black shale and light gray siltstone,abundant argillaceous laminas and silty laminas,with obvious lithological boundaries having developed.Horizontal laminas and rhythmic laminas are well-developed in the shale layer,while the wavy laminas are well-developed in the siltstone layer.2)The major compositional elements are SiO2,Al2O3 and CaO,followed by Fe_(2)O_(3),MgO,K_(2)O and Na_(2)O.3)Compared with the world average shale,these siltstone-mudstone rhythmic sedimentary sections are rich in Mo,U and Ba,but less in V,Co,Ni,Cu.Compared with the shale layer,the siltstone layer has lower contents of V,Co and Ni.4).The geochemical redox indices,Mo-U and CIA values suggest the formation of the siltstone-mudstone rhythmic sedimentary sections are related to influences from bottom currents in an oxic condition with a warm and humid paleoclimate.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11872105,12072022,11911530176,and 12202039)。
文摘In this paper,the dispersion,attenuation,and bandgap characteristics of in-plane coupled Bloch waves in one-dimensional piezoelectric semiconductor(PSC)phononic crystals are investigated,emphasizing the influence of positive-negative(PN)junctions.Unlike piezoelectric phononic crystals,the coupled Bloch waves in PSC phononic crystals are attenuated due to their semiconductor properties,and thus the solution of Bloch waves becomes more complicated.The transfer matrix of the phononic crystal unit cell is obtained using the state transfer equation.By applying the Bloch theorem for periodic structures,the dispersion relation of the coupled Bloch waves is derived,and the dispersion,attenuation,and bandgap are obtained in the complex wave number domain.It is found that the influence of the PN junction cannot be neglected.Moreover,the effects of the PN junction under different apparent wave numbers and steady-state carrier concentrations are provided.This indicates the feasibility of adjusting the propagation characteristics of Bloch waves through the regulation of the PN heterojunction.
基金Project supported by the National Natural Science Foundation of China(Nos.12202039,52204085,and 52474123)。
文摘This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylinder structure.This PS concentric cylinder structure is composed of three regions:an inner PS cylinder,an outer PS cylindrical shell,and a cylindrical PN junction at the interface between the two aforementioned regions.First,the basic equations of the PS concentric cylinder structure are derived,taking into account the coupling of the mechanical displacement,electric potential,and charge carrier perturbation in the cylindrical coordinate system.Next,a mathematical model for the SCWs in this PS concentric cylinder structure is established,utilizing the spectral method and considering the physical characteristics of the cylindrical PN junction.Finally,the dispersion and attenuation curves of the SCWs are numerically calculated to discuss the influence of the interface effect resulting from the cylindrical PN junction.It is found that the existence of a cylindrical PN junction can either reduce or enhance the mechanical-to-electrical energy conversion,which is closely related to the doping mode,doping concentration,and curvature radius of the cylindrical interface.A reasonable design of the aforementioned parameters can optimize the wave motion in acoustic equipment formed by PS media with different frequencies or wavelengths.The construction and resolution of the mathematical model as well as the analysis of physical mechanisms can offer theoretical guidance for improving the efficiency of energy conversion from mechanical energy to electrical energy and optimizing the acoustic performance of energy harvesting devices.
基金supported by the National Natural Science Foundation of China(Grant No.41602147)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX020000).
文摘The Lower Member of the Longrnaxi Forma-tion is generally dominated by siliceous shale,but recently we found some siltstone-mudstone rhythm sections developed in the Lower Member of the Longmaxi Formation.The study of formation mechanism of siltstone-mudstone rhythmic sedimentary sections may provide new insights into the shale sedimentary environ-ment.Therefore,we studied the characteristics and formation mechanism of siltstone-mudstone rhythmic sedimentary sections in the Lower Member of the Long-maxi Formation in the Changning area based on core observation,thin section identification,major elements and trace elements analysis.The results show the following:1)Two siltstone-mudstone rhythmic sedimentary sections are characterized by frequent interbed between black or gray-black shale and light gray siltstone,abundant argillaceous laminas and silty laminas,with obvious lithological boundaries having developed.Horizontal laminas and rhythmic laminas are well-developed in the shale layer,while the wavy laminas are well-developed in the siltstone layer.2)The major compositional elements are SiO2,Al2O3 and CaO,followed by Fe_(2)O_(3),MgO,K_(2)O and Na_(2)O.3)Compared with the world average shale,these siltstone-mudstone rhythmic sedimentary sections are rich in Mo,U and Ba,but less in V,Co,Ni,Cu.Compared with the shale layer,the siltstone layer has lower contents of V,Co and Ni.4).The geochemical redox indices,Mo-U and CIA values suggest the formation of the siltstone-mudstone rhythmic sedimentary sections are related to influences from bottom currents in an oxic condition with a warm and humid paleoclimate.
