The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to meas...The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to measure the separate electron and positron spectra,as well as the positron fraction.In this study,the Earth's magnetic field is used to distinguish CR electrons and positrons,as the DAMPE detector does not carry an onboard magnet.The energy for the measurements ranges from 10 to 20 GeV,which is currently limited at high energy by the zenith-pointing orientation of DAMPE.The results are consistent with previous measurements based on the magnetic spectrometer by AMS-02 and PAMELA,whereas the results of Fermi-LAT appear to be systematically shifted to larger values.展开更多
Single crystals of(1x) Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-xPT)near their morphotropic phase boundaries(MPBs)are under extensive investigations for their extraordinary high dielectric and piezoelectric behavior.Ap...Single crystals of(1x) Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-xPT)near their morphotropic phase boundaries(MPBs)are under extensive investigations for their extraordinary high dielectric and piezoelectric behavior.Applications of those single crystals facilitated the breakthrough in ultrasonic transducer materials and devices.Ferroelectric materials are known to be fragile which often leads to various reliability failures in applications involving electric loadings.In a mechanical sense,the failure modes concern the fracture under an intensive electric field,and the fatigue crack propagation under an alternating electric field.In an electrical sense,the failure is exhibited by degenerated hysteresis loop by shrinking the remnant polarization and expanding the coercive field.All these modes degrade the performance for ferroelectric devices.As a departure from the tetragonal TÞferroelectric materials,exemplified by BaTiO_(3) and Pb(ZrTi)O_(3),the domain structures of PMN-PT around the MPB are versatile and intricate,depending sensitively on the composition variation,orientation and previous loading history.In this review,the attention is mainly focused on three aspects.First,the phase fragility and multiphase coexistence are presented for both[100]-and[101]-oriented PMN-PT single crystals.Second,investigations on electric field-induced fatigue crack propagation are described,along with the orientation effect on the crack propagation behavior.Third,the inverse effects of the phase transition and fatigue crack growth on the polarization behavior,or the interaction between the mechanical and electrical degradations will be elucidated.The review aims for better understanding the underlying mechanism for the ultrahigh performance of the PMN-PT single crystals,to bridge the studies of ferroelectric materials from the mechanical and electrical senses,as well as to evaluate the reliability of PMN-PT single crystals under device applications.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFF0503303)the National Natural Science Foundation of China(Nos.12220101003,12275266,12003076,12022503,12103094 and U2031149)+8 种基金Outstanding Youth Science Foundation of NSFC(No.12022503)the Project for Young Scientists in Basic Research of the Chinese Academy of Sciences(No.YSBR-061)the Strategic Priority Program on Space Science of Chinese Academy of Sciences(No.E02212A02S)the Youth Innovation Promotion Association of CAS(No.2021450)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20220197)the New Cornerstone Science Foundation through the XPLORER PRIZEthe Program for Innovative Talents and Entrepreneur in Jiangsu.In Europesupported by the Swiss National Science Foundation(SNSF),Switzerland,the National Institute for Nuclear Physics(INFN),Italythe European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(No.851103).
文摘The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to measure the separate electron and positron spectra,as well as the positron fraction.In this study,the Earth's magnetic field is used to distinguish CR electrons and positrons,as the DAMPE detector does not carry an onboard magnet.The energy for the measurements ranges from 10 to 20 GeV,which is currently limited at high energy by the zenith-pointing orientation of DAMPE.The results are consistent with previous measurements based on the magnetic spectrometer by AMS-02 and PAMELA,whereas the results of Fermi-LAT appear to be systematically shifted to larger values.
基金supports by the National Natural Science Foundation of China through Grant No.10772090National Basic Research Program of China through Grant No.2004CB619304,are greatly acknowledged.
文摘Single crystals of(1x) Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-xPT)near their morphotropic phase boundaries(MPBs)are under extensive investigations for their extraordinary high dielectric and piezoelectric behavior.Applications of those single crystals facilitated the breakthrough in ultrasonic transducer materials and devices.Ferroelectric materials are known to be fragile which often leads to various reliability failures in applications involving electric loadings.In a mechanical sense,the failure modes concern the fracture under an intensive electric field,and the fatigue crack propagation under an alternating electric field.In an electrical sense,the failure is exhibited by degenerated hysteresis loop by shrinking the remnant polarization and expanding the coercive field.All these modes degrade the performance for ferroelectric devices.As a departure from the tetragonal TÞferroelectric materials,exemplified by BaTiO_(3) and Pb(ZrTi)O_(3),the domain structures of PMN-PT around the MPB are versatile and intricate,depending sensitively on the composition variation,orientation and previous loading history.In this review,the attention is mainly focused on three aspects.First,the phase fragility and multiphase coexistence are presented for both[100]-and[101]-oriented PMN-PT single crystals.Second,investigations on electric field-induced fatigue crack propagation are described,along with the orientation effect on the crack propagation behavior.Third,the inverse effects of the phase transition and fatigue crack growth on the polarization behavior,or the interaction between the mechanical and electrical degradations will be elucidated.The review aims for better understanding the underlying mechanism for the ultrahigh performance of the PMN-PT single crystals,to bridge the studies of ferroelectric materials from the mechanical and electrical senses,as well as to evaluate the reliability of PMN-PT single crystals under device applications.
