Rainbow piezoelectric ceramics are a new type of stress-biased,oxide-reduced composite ferroelectric ceramics,which have a special dome structure.The have shown excellent properties such as ultra-high displacement und...Rainbow piezoelectric ceramics are a new type of stress-biased,oxide-reduced composite ferroelectric ceramics,which have a special dome structure.The have shown excellent properties such as ultra-high displacement under an applied electric field and enhanced load-bearing capability.In this article,their manufacture,structures and properties were discussed in detail by combining experiments and theory analysis.The resuts show that the optimal conditions for producing Rainbow samples from PLZT ceramics were determined to be 900℃ for 1 to 1.5 hours.A number of different phases have been found in the reduced layer of Rainbow ceramics by XRD analyses.The phases found include metallic lead and other oxide phases,such as PbO,ZrO 2 and TiO 2.The original PLZT phase was not observed.The reduced layer was transgranularly fractured while the unreduced ceramic was intergranularly fractured.Two kinds of fracture types can be seen at the interface,which denotes the different degrees of reduction.It is shown that the Pb grains (about 0.2μm) constitute a continuous phase in the reduced layer,which accounts for the good electrical conductivity.展开更多
A new type of large-displacement actuating materials called RAINBOW (Reduced and Internally Biased Oxide Wafer) ceramics is fabricated by a chemical reduction of PLZT piezoelectric ceramics. It is found that PLZT is e...A new type of large-displacement actuating materials called RAINBOW (Reduced and Internally Biased Oxide Wafer) ceramics is fabricated by a chemical reduction of PLZT piezoelectric ceramics. It is found that PLZT is easily reduced and the thickness of reduced layer has a linear relationship with the reduction time. The optimal conditions for producing RAINBOW samples from PLZT are determined to be 950℃ for 1-1.5 hours. SEM micrograph shows that the RAINBOW ceramics are composed of reduced and unreduced layer obviously. And the reduced layer is transgranularly fractured while the unreduced ceramic is intergranularly fractured. Metallic lead and refractor oxides (PbO, ZrO_2, ZrTiO_4, etc.) are found in the reduced layer by XRD analyses, however, the crystal structure of PLZT is not found. The analysis of the reduction mechanism is in good accordance with experimental data.展开更多
In the past few decades,robotics research has witnessed an increasingly high interest in miniaturized,intelligent,and integrated robots.The imperative component of a robot is the actuator that determines its performan...In the past few decades,robotics research has witnessed an increasingly high interest in miniaturized,intelligent,and integrated robots.The imperative component of a robot is the actuator that determines its performance.Although traditional rigid drives such as motors and gas engines have shown great prevalence in most macroscale circumstances,the reduction of these drives to the millimeter or even lower scale results in a significant increase in manufacturing difficulty accompanied by a remarkable performance decline.Biohybrid robots driven by living cells can be a potential solution to overcome these drawbacks by benefiting from the intrinsic microscale self-assembly of living tissues and high energy efficiency,which,among other unprecedented properties,also feature flexibility,self-repair,and even multiple degrees of freedom.This paper systematically reviews the development of biohybrid robots.First,the development of biological flexible drivers is introduced while emphasizing on their advantages over traditional drivers.Second,up-to-date works regarding biohybrid robots are reviewed in detail from three aspects:biological driving sources,actuator materials,and structures with associated control methodologies.Finally,the potential future applications and major challenges of biohybrid robots are explored.展开更多
The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field ...The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field concentrations ahead of the electrodes in the multilayer piezoelectric actuators are examined. By considering a representative unit in realistic multilayers, the problem is formulated in terms of electric potential between the electrode tips and results in a system of singular integral equations in which the electric potential is taken as unknown function. Effects are investigated of electrode spacing and piezoelectric coupling on the singular electroelastic fields at the electrode tips, and closed-form expressions are given for the electromechanical field near the electrode tips. Exact solution for un-coupled dielectrics is provided, where no piezoelectric coupling is present.展开更多
文摘Rainbow piezoelectric ceramics are a new type of stress-biased,oxide-reduced composite ferroelectric ceramics,which have a special dome structure.The have shown excellent properties such as ultra-high displacement under an applied electric field and enhanced load-bearing capability.In this article,their manufacture,structures and properties were discussed in detail by combining experiments and theory analysis.The resuts show that the optimal conditions for producing Rainbow samples from PLZT ceramics were determined to be 900℃ for 1 to 1.5 hours.A number of different phases have been found in the reduced layer of Rainbow ceramics by XRD analyses.The phases found include metallic lead and other oxide phases,such as PbO,ZrO 2 and TiO 2.The original PLZT phase was not observed.The reduced layer was transgranularly fractured while the unreduced ceramic was intergranularly fractured.Two kinds of fracture types can be seen at the interface,which denotes the different degrees of reduction.It is shown that the Pb grains (about 0.2μm) constitute a continuous phase in the reduced layer,which accounts for the good electrical conductivity.
文摘A new type of large-displacement actuating materials called RAINBOW (Reduced and Internally Biased Oxide Wafer) ceramics is fabricated by a chemical reduction of PLZT piezoelectric ceramics. It is found that PLZT is easily reduced and the thickness of reduced layer has a linear relationship with the reduction time. The optimal conditions for producing RAINBOW samples from PLZT are determined to be 950℃ for 1-1.5 hours. SEM micrograph shows that the RAINBOW ceramics are composed of reduced and unreduced layer obviously. And the reduced layer is transgranularly fractured while the unreduced ceramic is intergranularly fractured. Metallic lead and refractor oxides (PbO, ZrO_2, ZrTiO_4, etc.) are found in the reduced layer by XRD analyses, however, the crystal structure of PLZT is not found. The analysis of the reduction mechanism is in good accordance with experimental data.
基金the Research Project Funding of National University of Defense Technology of China(No.ZK19-33)the National Postdoctoral International Exchange Program Funding for Incoming Postdoctoral Students(postdoctoral No.48127).
文摘In the past few decades,robotics research has witnessed an increasingly high interest in miniaturized,intelligent,and integrated robots.The imperative component of a robot is the actuator that determines its performance.Although traditional rigid drives such as motors and gas engines have shown great prevalence in most macroscale circumstances,the reduction of these drives to the millimeter or even lower scale results in a significant increase in manufacturing difficulty accompanied by a remarkable performance decline.Biohybrid robots driven by living cells can be a potential solution to overcome these drawbacks by benefiting from the intrinsic microscale self-assembly of living tissues and high energy efficiency,which,among other unprecedented properties,also feature flexibility,self-repair,and even multiple degrees of freedom.This paper systematically reviews the development of biohybrid robots.First,the development of biological flexible drivers is introduced while emphasizing on their advantages over traditional drivers.Second,up-to-date works regarding biohybrid robots are reviewed in detail from three aspects:biological driving sources,actuator materials,and structures with associated control methodologies.Finally,the potential future applications and major challenges of biohybrid robots are explored.
文摘The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field concentrations ahead of the electrodes in the multilayer piezoelectric actuators are examined. By considering a representative unit in realistic multilayers, the problem is formulated in terms of electric potential between the electrode tips and results in a system of singular integral equations in which the electric potential is taken as unknown function. Effects are investigated of electrode spacing and piezoelectric coupling on the singular electroelastic fields at the electrode tips, and closed-form expressions are given for the electromechanical field near the electrode tips. Exact solution for un-coupled dielectrics is provided, where no piezoelectric coupling is present.
