Piezoelectric energy harvesting is widely used to scavenge vibration energy in the environment.For some vibration sources with fixed frequency,cantilevered harvester can generate the energy effectively,so the optimiza...Piezoelectric energy harvesting is widely used to scavenge vibration energy in the environment.For some vibration sources with fixed frequency,cantilevered harvester can generate the energy effectively,so the optimization theory for cantilevered harvester in such an application is needed.In this article,we present the theoretical and experimental studies of the cantilevered piezoelectric energy harvester with a fixed resonance frequency.An analytical model based on energy method is used to estimate the open-circuit voltage and generated energy.Considering that the harvester may be subjected to the static force or steady-state sinusoidal vibration excitation,static and dynamic analysis is performed for device structure to achieve efficient energy.In the analysis,the effects of geometrical dimension on the energy harvesting performance are discussed comprehensively.Eventually,a prototype is designed and fabricated using(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-PT)single crystal with ultrahigh piezoelectric properties and coupling factor.Performances of the cantilever with different clamped length are evaluated under sinusoidal vibration excitation,proving the good consistency between experimental results and theoretical prediction.The established analysis can provide useful guidelines for the structure design of cantilevered piezoelectric energy harvester with a fixed resonance frequency.展开更多
The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the applicat...The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the application of dc bias ranging from 1.5 to 4.0 kV/cm, the dielectric spectrum of a [001] oriented single crystal showed an abnormal dielectric peak within the rhombic phase-stable temperature range. However, this peak disappeared at E>4.0 kV/cm and was not yet found in the [111] oriented single crystal. The abnormal dielectric peak was attributed to the filed-induced phase transition.展开更多
Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecu...Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.展开更多
基金supported by the Natural Basic Research Program of China("973"Program)(Grant No.2013CB632902)the National Natural Science Foundation of China(Grant Nos.51332009,51372258,11304333 and 51272268)
文摘Piezoelectric energy harvesting is widely used to scavenge vibration energy in the environment.For some vibration sources with fixed frequency,cantilevered harvester can generate the energy effectively,so the optimization theory for cantilevered harvester in such an application is needed.In this article,we present the theoretical and experimental studies of the cantilevered piezoelectric energy harvester with a fixed resonance frequency.An analytical model based on energy method is used to estimate the open-circuit voltage and generated energy.Considering that the harvester may be subjected to the static force or steady-state sinusoidal vibration excitation,static and dynamic analysis is performed for device structure to achieve efficient energy.In the analysis,the effects of geometrical dimension on the energy harvesting performance are discussed comprehensively.Eventually,a prototype is designed and fabricated using(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-PT)single crystal with ultrahigh piezoelectric properties and coupling factor.Performances of the cantilever with different clamped length are evaluated under sinusoidal vibration excitation,proving the good consistency between experimental results and theoretical prediction.The established analysis can provide useful guidelines for the structure design of cantilevered piezoelectric energy harvester with a fixed resonance frequency.
基金This work was supprted by the University Key Studies Project of Shanghai.
文摘The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the application of dc bias ranging from 1.5 to 4.0 kV/cm, the dielectric spectrum of a [001] oriented single crystal showed an abnormal dielectric peak within the rhombic phase-stable temperature range. However, this peak disappeared at E>4.0 kV/cm and was not yet found in the [111] oriented single crystal. The abnormal dielectric peak was attributed to the filed-induced phase transition.
基金financial supports from the National Natural Science Foundation of China (11974222,12004226,12174229,11904214)Natural Science Foundation of Shandong Province (ZR2022YQ02,ZR2020QA075)+2 种基金Qingchuang Science and Technology Plan of Shandong Province (2021KJ006,2019KJJ014,2019KJJ017)Taishan Scholars Program of Shandong Province (tsqn202306152)China Postdoctoral Science Foundation(2019M662423),Shandong Post-Doctoral Innovation Project (202002021).
文摘Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.
