(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_(3)+x%Ce_(2)O_(3)+y%La_(2)O_(3)+z%Y_(2)O_(3) compounds(named BNT-BT-x/y/z)were synthesized by a sol-gel technique,for (x,y,z)=(0,0,0),(0.25,0.25,0.25),(0.25,0.5,0.5),(0.5,0.25,0.2...(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_(3)+x%Ce_(2)O_(3)+y%La_(2)O_(3)+z%Y_(2)O_(3) compounds(named BNT-BT-x/y/z)were synthesized by a sol-gel technique,for (x,y,z)=(0,0,0),(0.25,0.25,0.25),(0.25,0.5,0.5),(0.5,0.25,0.25)and(0.5,0.5,0.25).The structural variation according to the different system compositions is investigated by X-ray diffraction analyses.The results shows that the addition of Ce_(2)O_(3),La_(2)O_(3) or Y_(2)O_(3) in BNT-BT system,do not modify the crystalline structure,and a rhombohedral-tetragonal morphotropic phase boundary is maintained for different dopant addition.The BNT-BT-x/y/z-based ceramics sintered at relatively low temperature(1100℃)exhibit a good densification ratio.The optimum dielectric and piezoelectric properties are obtained with the BNT-BT-0.5/0.25/0.25 composition.High dielectric properties at room temperature(ε_(r)>1000)and low dielectric losses(tanδ<4×10^(-2))are obtained for this composition.This compound exhibits a piezoelectric constant d_(33) of 95 pC/N,a good polarization behavior is observed with high remanent polarization P_(r) of 9.21μC/cm^(2) and low value coercitivefield E_(c) of 2.66 kV/mm.展开更多
Solid solutions based on Li,Ta and Sb-doped(K_(0.5)Na_(0.5))NbO_(3)(KNN)lead-free perovskite systems were created using standard solid-state methods.X-ray diffraction was used to conrm that all compositions were singl...Solid solutions based on Li,Ta and Sb-doped(K_(0.5)Na_(0.5))NbO_(3)(KNN)lead-free perovskite systems were created using standard solid-state methods.X-ray diffraction was used to conrm that all compositions were single phase and to verify the phase transition from tetragonal to cubic at T_(C)=302℃.The three compositions examined,originally developed by Saito and Li,were shown to be strongly ferroelectric with sharp peaks in permittivity present at the Curie temperature.The optimum composition had loss tangent values below 5%up to 100 kHz at room temperature.Bipolar hysteresis measurements showed high values for both maximum polarization(25 and 21μC/cm^(2))and remenant polarizations(20 and 16μC/cm^(2))for undoped and 0.2 wt%CuO-doped samples.Maximum strain values of greater than 0.23%were observed.展开更多
Lead-free piezoelectric ceramics （1-y）Bi0.5（Na1-xLix）0.5TiO3-yBaTiO3 with x=0-0.125 and y=0.02-0.12 were fabricated by a solid-state reaction process, and their dielectric, piezoelectric and ferroelectric properti...Lead-free piezoelectric ceramics （1-y）Bi0.5（Na1-xLix）0.5TiO3-yBaTiO3 with x=0-0.125 and y=0.02-0.12 were fabricated by a solid-state reaction process, and their dielectric, piezoelectric and ferroelectric properties were investigated. The results show that the addition of Li^＋ significantly improves the sintering performance and piezoelectric properties of the ceramics. X-ray diffraction （XRD） patterns indicate that the ceramics possess pure perovskite structure. At room temperature, the ceramics provide high piezoelectric charge constant d33 （up to 210 pC/N）, high planar electromechanical coupling factor kp （34.5%）, large remanent polarization Pr （up to 40 μC/cm^2）, and low coercive field Ec （3.0 kV/mm）, which indicates that （1-y）Bi0.5（Na1-xLix）0.5TiO3-yBaTi03 is a good lead-free piezoelectric ceramic.展开更多
基金Supported by basic research foundation of northwestern polytechnical university,and postgraduate starting seed foundation of northwestern polytechnical university (Z2010009)~~
基金Supported by Basic Research Foundation of Northwestern Polytechnical University(G9KY101902)Postgraduate Starting Seed Foundation of Northwestern Polytechnical University(Z2011003)~~
文摘(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_(3)+x%Ce_(2)O_(3)+y%La_(2)O_(3)+z%Y_(2)O_(3) compounds(named BNT-BT-x/y/z)were synthesized by a sol-gel technique,for (x,y,z)=(0,0,0),(0.25,0.25,0.25),(0.25,0.5,0.5),(0.5,0.25,0.25)and(0.5,0.5,0.25).The structural variation according to the different system compositions is investigated by X-ray diffraction analyses.The results shows that the addition of Ce_(2)O_(3),La_(2)O_(3) or Y_(2)O_(3) in BNT-BT system,do not modify the crystalline structure,and a rhombohedral-tetragonal morphotropic phase boundary is maintained for different dopant addition.The BNT-BT-x/y/z-based ceramics sintered at relatively low temperature(1100℃)exhibit a good densification ratio.The optimum dielectric and piezoelectric properties are obtained with the BNT-BT-0.5/0.25/0.25 composition.High dielectric properties at room temperature(ε_(r)>1000)and low dielectric losses(tanδ<4×10^(-2))are obtained for this composition.This compound exhibits a piezoelectric constant d_(33) of 95 pC/N,a good polarization behavior is observed with high remanent polarization P_(r) of 9.21μC/cm^(2) and low value coercitivefield E_(c) of 2.66 kV/mm.
文摘Solid solutions based on Li,Ta and Sb-doped(K_(0.5)Na_(0.5))NbO_(3)(KNN)lead-free perovskite systems were created using standard solid-state methods.X-ray diffraction was used to conrm that all compositions were single phase and to verify the phase transition from tetragonal to cubic at T_(C)=302℃.The three compositions examined,originally developed by Saito and Li,were shown to be strongly ferroelectric with sharp peaks in permittivity present at the Curie temperature.The optimum composition had loss tangent values below 5%up to 100 kHz at room temperature.Bipolar hysteresis measurements showed high values for both maximum polarization(25 and 21μC/cm^(2))and remenant polarizations(20 and 16μC/cm^(2))for undoped and 0.2 wt%CuO-doped samples.Maximum strain values of greater than 0.23%were observed.
基金supported by the National Nat-ural Science Foundation of China (No 50572066)the Sichuan Provincial Department of Education, China (No2006A075)the Doctor Start-up Foundation of China West Normal University (No 06B059)
文摘Lead-free piezoelectric ceramics （1-y）Bi0.5（Na1-xLix）0.5TiO3-yBaTiO3 with x=0-0.125 and y=0.02-0.12 were fabricated by a solid-state reaction process, and their dielectric, piezoelectric and ferroelectric properties were investigated. The results show that the addition of Li^＋ significantly improves the sintering performance and piezoelectric properties of the ceramics. X-ray diffraction （XRD） patterns indicate that the ceramics possess pure perovskite structure. At room temperature, the ceramics provide high piezoelectric charge constant d33 （up to 210 pC/N）, high planar electromechanical coupling factor kp （34.5%）, large remanent polarization Pr （up to 40 μC/cm^2）, and low coercive field Ec （3.0 kV/mm）, which indicates that （1-y）Bi0.5（Na1-xLix）0.5TiO3-yBaTi03 is a good lead-free piezoelectric ceramic.
