The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic pha...The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic phase boundary(PPB).This study,however,unveils a distinct piezoelectric enhancement mechanism in the xPb(Nb_(2/3)Ni_(1/3))O_(3)-(1-x)Pb(Zr_(0.3)Ti_(0.7))O_(3)(PNN-PZT)system,diverging from the MPB/PPB-centered piezoelectric systems.Notably,the composition with x=0.55,positioned close to the tetragonal-pseudocubic(T-PC)phase boundary,achieves an unprecedented piezoelectric coefficient(d_(33))of 1264 pC/N,while retaining a tetragonal local structure.Importantly,on a local scale,electric fields do not in-cite phase transitions,suggesting that the exceptional piezoelectric performance in PNN-PZT stems from polarization extension near the T-PC boundary.Distinct from other mechanisms,the relative permittivity significantly increases post-poling due to this particular enhancement process.The dielectric behavior in poled specimens does not exhibit a conspicuous change at the ferroelectric-relaxor transition tempera-ture.However,both the relative permittivity and planar electromechanical coupling coefficient experience a sharp rise in the temperature range of−25℃to 25℃.This investigation underscores the pivotal role of designing compositionally-driven T-PC phase boundaries,presenting a promising avenue for enhancing piezoelectric properties in ferroelectric ceramics.展开更多
Due to the remarkable magnetoresistance (MR) effect on perovskite-type manganite, magnetoelectronics and spintronics have become attractive subjects of experimental and theoretical investigations for the application p...Due to the remarkable magnetoresistance (MR) effect on perovskite-type manganite, magnetoelectronics and spintronics have become attractive subjects of experimental and theoretical investigations for the application purpose. (La0.9Nd0.1)2/3Ca1/3Mn1-xFexO3(x=0, x=0.05) were prepared successfully by sol-gel method. The structure, magnetic properties, and transport properties of the compounds were investigated. The magnetoresistance effect depends on the composition and the temperature. XRD patterns show that the compound is a single phase polycrystal with pseudocubic structure. A large negative isotropic magnetoresistance effect in the samples were observed at low temperature region. The maximum MR of the samples was 77% and 97%, respectively. It was most likely due to the scattering or the tunneling transport of spin-polarized carriers in lattice under strong magnetic field.展开更多
基金financially supported by the National Natu-ral Science Foundation of China(Project No.11704301)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2022JM212).
文摘The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic phase boundary(PPB).This study,however,unveils a distinct piezoelectric enhancement mechanism in the xPb(Nb_(2/3)Ni_(1/3))O_(3)-(1-x)Pb(Zr_(0.3)Ti_(0.7))O_(3)(PNN-PZT)system,diverging from the MPB/PPB-centered piezoelectric systems.Notably,the composition with x=0.55,positioned close to the tetragonal-pseudocubic(T-PC)phase boundary,achieves an unprecedented piezoelectric coefficient(d_(33))of 1264 pC/N,while retaining a tetragonal local structure.Importantly,on a local scale,electric fields do not in-cite phase transitions,suggesting that the exceptional piezoelectric performance in PNN-PZT stems from polarization extension near the T-PC boundary.Distinct from other mechanisms,the relative permittivity significantly increases post-poling due to this particular enhancement process.The dielectric behavior in poled specimens does not exhibit a conspicuous change at the ferroelectric-relaxor transition tempera-ture.However,both the relative permittivity and planar electromechanical coupling coefficient experience a sharp rise in the temperature range of−25℃to 25℃.This investigation underscores the pivotal role of designing compositionally-driven T-PC phase boundaries,presenting a promising avenue for enhancing piezoelectric properties in ferroelectric ceramics.
文摘Due to the remarkable magnetoresistance (MR) effect on perovskite-type manganite, magnetoelectronics and spintronics have become attractive subjects of experimental and theoretical investigations for the application purpose. (La0.9Nd0.1)2/3Ca1/3Mn1-xFexO3(x=0, x=0.05) were prepared successfully by sol-gel method. The structure, magnetic properties, and transport properties of the compounds were investigated. The magnetoresistance effect depends on the composition and the temperature. XRD patterns show that the compound is a single phase polycrystal with pseudocubic structure. A large negative isotropic magnetoresistance effect in the samples were observed at low temperature region. The maximum MR of the samples was 77% and 97%, respectively. It was most likely due to the scattering or the tunneling transport of spin-polarized carriers in lattice under strong magnetic field.
