To address the urgent demand for the miniaturization and multifunctional integration of high-frequency Rayleigh surface wave devices in 5G communication technology,the propagation characteristics of Rayleigh surface w...To address the urgent demand for the miniaturization and multifunctional integration of high-frequency Rayleigh surface wave devices in 5G communication technology,the propagation characteristics of Rayleigh surface waves in an elastic half-space attached by a nanoscale piezoelectric semiconductor(PSC)thin layer with flexoelectricity and size-effects are systematically investigated.Based on the Hamiltonian principle,the elastic dynamic equations and Gauss's theorem of electrostatics are obtained.The eigenvalue problem is numerically solved with a genetic algorithm in MATLAB,and the dispersion properties are obtained.The effects of various key factors,including the flexoelectricity,inertia gradients,strain gradients,electric field gradients,PSC layer thickness,steady-state carrier concentration,and bias electric fields,on the propagation and attenuation characteristics of Rayleigh surface waves are analyzed.The results demonstrate that the increases in the flexoelectric coefficient and strain gradient characteristic length lead to an increase in the real part of the complex phase velocity,while the increases in the inertia gradient characteristic length,electric field gradient characteristic length,PSC layer thickness,and steady-state carrier concentration result in a decrease.Additionally,the bias electric fields significantly influence the Rayleigh surface wave attenuation.The present findings are crucial for the accurate property evaluation of miniaturized highfrequency Rayleigh wave devices,and provide valuable theoretical support for their design and optimization.展开更多
Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditio...Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditions of heat treatment.the results show that the tetragonal symmetry is reduced and the ferroelectricparaelectric phase transformation temperature is decreased with the reduce of the grainsize of the sample.the critical grainsize for the ferroelectricparaelectric phase transformation at room temperature was calculated.The change regularities of the lattice constant and tetragonality with the grainsize are discussed.展开更多
The activation of CO_(2)molecules is a fundamental step for their effective utilization.Constructing highdensity oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO_(2).In this work...The activation of CO_(2)molecules is a fundamental step for their effective utilization.Constructing highdensity oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO_(2).In this work,we prepared a series of 0.5PtxCe/Al_(2)O_(3)(x=1,5,10,or 20)catalysts with varying Ce loading and 0.5 wt%of Pt for the reverse water gas shift(RWGS)reaction.The size of CeO_(2)particle increases with Ce loading.Remarkably,the 0.5Pt5Ce/Al_(2)O_(3) catalyst with an average CeO_(2)particle size of 5.5 nm exhibits a very high CO_(2)conversion rate(116.4×10^(-5)mol_(CO_(2))/(g_(cat)·s))and CO selectivity(96.1%)at 600℃.Our experimental findings reveal that the small-size CeO_(2)in 0.5Pt5Ce/Al_(2)O_(3) possesses a greater capacity to generate reactive oxygen vacancies,promoting the adsorption and activation of CO_(2).In addition,the oxygen vacancies are cyclically generated and consumed during the reaction,which contributes to the elevated catalytic performance of the catalyst.This work provides a general strategy to construct rich oxygen vacancies on CeO_(2)for designing high-performance catalysts in C_(1) chemistry.展开更多
基金supported by the Singapore Ministry of Education(MOE)Academic Research Fund(AcRF)Tier 1(Nos.RG145/23 and RG78/24)the National Natural Science Foundation of China(No.U24A2005)Ningbo Natural Science Foundation(No.2024J183)。
文摘To address the urgent demand for the miniaturization and multifunctional integration of high-frequency Rayleigh surface wave devices in 5G communication technology,the propagation characteristics of Rayleigh surface waves in an elastic half-space attached by a nanoscale piezoelectric semiconductor(PSC)thin layer with flexoelectricity and size-effects are systematically investigated.Based on the Hamiltonian principle,the elastic dynamic equations and Gauss's theorem of electrostatics are obtained.The eigenvalue problem is numerically solved with a genetic algorithm in MATLAB,and the dispersion properties are obtained.The effects of various key factors,including the flexoelectricity,inertia gradients,strain gradients,electric field gradients,PSC layer thickness,steady-state carrier concentration,and bias electric fields,on the propagation and attenuation characteristics of Rayleigh surface waves are analyzed.The results demonstrate that the increases in the flexoelectric coefficient and strain gradient characteristic length lead to an increase in the real part of the complex phase velocity,while the increases in the inertia gradient characteristic length,electric field gradient characteristic length,PSC layer thickness,and steady-state carrier concentration result in a decrease.Additionally,the bias electric fields significantly influence the Rayleigh surface wave attenuation.The present findings are crucial for the accurate property evaluation of miniaturized highfrequency Rayleigh wave devices,and provide valuable theoretical support for their design and optimization.
文摘Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditions of heat treatment.the results show that the tetragonal symmetry is reduced and the ferroelectricparaelectric phase transformation temperature is decreased with the reduce of the grainsize of the sample.the critical grainsize for the ferroelectricparaelectric phase transformation at room temperature was calculated.The change regularities of the lattice constant and tetragonality with the grainsize are discussed.
基金Project supported by the National Science Fund for Distinguished Young Scholars of China(22225110)the National Key Research and Development Program of China(2021YFA1501103)+1 种基金the National Science Foundation of China(22075166,22271177)the Young Scholars Program of Shandong University。
文摘The activation of CO_(2)molecules is a fundamental step for their effective utilization.Constructing highdensity oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO_(2).In this work,we prepared a series of 0.5PtxCe/Al_(2)O_(3)(x=1,5,10,or 20)catalysts with varying Ce loading and 0.5 wt%of Pt for the reverse water gas shift(RWGS)reaction.The size of CeO_(2)particle increases with Ce loading.Remarkably,the 0.5Pt5Ce/Al_(2)O_(3) catalyst with an average CeO_(2)particle size of 5.5 nm exhibits a very high CO_(2)conversion rate(116.4×10^(-5)mol_(CO_(2))/(g_(cat)·s))and CO selectivity(96.1%)at 600℃.Our experimental findings reveal that the small-size CeO_(2)in 0.5Pt5Ce/Al_(2)O_(3) possesses a greater capacity to generate reactive oxygen vacancies,promoting the adsorption and activation of CO_(2).In addition,the oxygen vacancies are cyclically generated and consumed during the reaction,which contributes to the elevated catalytic performance of the catalyst.This work provides a general strategy to construct rich oxygen vacancies on CeO_(2)for designing high-performance catalysts in C_(1) chemistry.
