The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically prac...The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.展开更多
Room-temperature fabrication of functional ceramic films using powder aerosol deposition(AD)is important for practical applications.However,the as-processed ferroelectric films show unusual temperature-dependent diele...Room-temperature fabrication of functional ceramic films using powder aerosol deposition(AD)is important for practical applications.However,the as-processed ferroelectric films show unusual temperature-dependent dielectric response,including enhanced conductivity in the as-processed state and subsequent significant increase in the permittivity following heat treatment.In this work,we investigate the influence of the residual internal stresses developed during the high-impact consolidation process on the dielectric response.Moreover,the recombination of charged defects generated during deposition is driven by the temperature and the atmospheric condition during the heat treatment as well as the carrier gas type used during deposition.Thermal treatment up to 500℃ in different atmospheres was used to tune the dielectric and ferroelectric response,highlighting that irrespective of the type of carrier gas,AD deposition process induces charged defects in polar oxide ceramics that can be reduced through heat-treatment far-below their bulk sintering temperature.Macroscopic electromechanical properties are contrasted to in-situ heating scanning transmission electron microscopy to observe possible local effects,such as crystallization,grain growth,crystal defect structure,or grain reorientation.In addition X-ray diffraction and X-ray photoelectron spectroscopy studies were conducted to gain insight into the effect of annealing on the crystal structure and local moisture adsorption.展开更多
In this study,the stress-modulated energy storage properties of lead-free polycrystalline Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)was investigated as a function of temperature from 25℃to 55℃.The externally applied un...In this study,the stress-modulated energy storage properties of lead-free polycrystalline Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)was investigated as a function of temperature from 25℃to 55℃.The externally applied uniaxial compressive stress of-160 MPa increased the recoverable energy storage density by 226%to a maximum value of 274 mJ/cm^(3),in addition to enhancing the energy storage efficiency by approximately 10%to a value of 88.2%.The macroscopic mechanical constitutive behavior is presented as well as the stress-dependent dielectric and ferroelectric properties and the Rayleigh behavior in order to elucidate the effect of stress on the energy storage properties.Importantly,the stress-induced tailoring of energy storage performance can be utilized for other nonlinear dielectric ceramics to tune their extrinsic polarization mechanisms to significantly enhance the recoverable energy density and reduce the hysteretic losses.展开更多
文摘The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.
基金financial support for this work from the Deutsche Forschungsgemeinschaft(DFG)under WE4972/2 and GRK2495Ffunding from the Slovenian Research Agency within programmes P2-0105 and P2-0393 and projects J2-2497,J2-3041,and bilateral project BIeDE/20-21-012.
文摘Room-temperature fabrication of functional ceramic films using powder aerosol deposition(AD)is important for practical applications.However,the as-processed ferroelectric films show unusual temperature-dependent dielectric response,including enhanced conductivity in the as-processed state and subsequent significant increase in the permittivity following heat treatment.In this work,we investigate the influence of the residual internal stresses developed during the high-impact consolidation process on the dielectric response.Moreover,the recombination of charged defects generated during deposition is driven by the temperature and the atmospheric condition during the heat treatment as well as the carrier gas type used during deposition.Thermal treatment up to 500℃ in different atmospheres was used to tune the dielectric and ferroelectric response,highlighting that irrespective of the type of carrier gas,AD deposition process induces charged defects in polar oxide ceramics that can be reduced through heat-treatment far-below their bulk sintering temperature.Macroscopic electromechanical properties are contrasted to in-situ heating scanning transmission electron microscopy to observe possible local effects,such as crystallization,grain growth,crystal defect structure,or grain reorientation.In addition X-ray diffraction and X-ray photoelectron spectroscopy studies were conducted to gain insight into the effect of annealing on the crystal structure and local moisture adsorption.
基金the financial support for this work from the Deutsche Forschungsgemeinschaft under GRK2945/F and H.
文摘In this study,the stress-modulated energy storage properties of lead-free polycrystalline Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)was investigated as a function of temperature from 25℃to 55℃.The externally applied uniaxial compressive stress of-160 MPa increased the recoverable energy storage density by 226%to a maximum value of 274 mJ/cm^(3),in addition to enhancing the energy storage efficiency by approximately 10%to a value of 88.2%.The macroscopic mechanical constitutive behavior is presented as well as the stress-dependent dielectric and ferroelectric properties and the Rayleigh behavior in order to elucidate the effect of stress on the energy storage properties.Importantly,the stress-induced tailoring of energy storage performance can be utilized for other nonlinear dielectric ceramics to tune their extrinsic polarization mechanisms to significantly enhance the recoverable energy density and reduce the hysteretic losses.
