The lead-free piezoelectric ceramics (K0.5Na0.5)NbO3 (abbreviated as KNN) with the relative density of 97.6% were synthesized by press-less sintering owing to the careful control of processing conditions. The phase st...The lead-free piezoelectric ceramics (K0.5Na0.5)NbO3 (abbreviated as KNN) with the relative density of 97.6% were synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics was analyzed. The results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of poling conditions on the piezoelectric properties of KNN ceramics was investigated. The results show that the piezoelectric constant d33 and electromechanical coupling factor kp increase with poling field, poling temperature and poling time increasing, then decrease because of electric broken. Take into account of poling conditions and piezoelectric properties of pure KNN ceramics, the optimum poling conditions for pure KNN ceramics are poling field of 4 kV/mm, poling temperature of 140℃and poling time of 20-25 min.展开更多
Piezoelectric ceramics of 0.6(Bi0.9La0.1)FeO3-0.4Pb(Ti1-xMnx)O3 (BLF-PTM) for x=0, 0.01, 0.02, and 0.03 were prepared by sol-gel process combined with a solid-state reaction method. The tan? for BLF-PTM of x=0.01 is j...Piezoelectric ceramics of 0.6(Bi0.9La0.1)FeO3-0.4Pb(Ti1-xMnx)O3 (BLF-PTM) for x=0, 0.01, 0.02, and 0.03 were prepared by sol-gel process combined with a solid-state reaction method. The tan? for BLF-PTM of x=0.01 is just 0.006 at 1 kHz, drastically decreasing by using Mn dopants. The TC increases to 490 ℃ for BLF-PTM of x=0.02. Furthermore, Mn modification effectively enhances the poling state and the piezoelectric properties of BLF-PTM. The kp, Qm, d33, and g33 of 0.34, 403, and 124 pC1·N-1 and 37×10-3 Vm·N-1 are achieved for BLF-PTM of x=0.01. The results indicate that Mn modified BLF-PTM is a competitive high power and high temperature piezoelectric material with excellent piezoelectric properties.展开更多
High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high perfo...High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high performance and superior thermal stability are hard to achieve simultaneously.Here we report that a high piezoelectricity(d_(33)∼562 pC/N)and superior thermal stability(the variation is within 7%from 20 to 330℃)were both achieved in 0.4 mol%ZnO-doped 0.02Pb(Sb_(1/2)Nb_(1/2))-0.51PbZrO_(3)-0.47PbTiO_(3) by high-temperature poling.Compared with traditional poling method,high-temperature poling method forms a small-sized and highly oriented domain structure,which can effectively improve the piezoelectric and dielectric properties of piezoelectric ceramics.At the same time,the enhanced pinning effect of defect ions and stabilized domain structure due to high-temperature poling also contribute to the superior temperature stability of the piezoelectric and dielectric properties.This work provides an effective method for designing piezoelectric materials with high performance and good temperature stability for high temperature sensor applications.展开更多
The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs p...The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs poled at high voltage(HV,5 kV_(rms)/cm)occasionally showed large fluctuations and low opposite values of piezoelectric coefficient(d_(33)=±1370 pC/N)in one plate.This revealed spuriousmode vibrations(SMV)of impedance spectrum.However,after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage(LV,3.5 kV_(rms)/cm),the d_(33) enhanced to be 1720 pC/N(+26%)and did not exhibit large fluctuation or opposite values in one plate any more.The impedance spectrum became clean and the abnormal SMV disappeared.We proposed four possible mechanisms of the SMV,and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs.This study will be useful to realize a high d_(33) and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.展开更多
Lead-free(K_(0.4425)Na_(0.52)Li_(0.0375))(Nb_(0.8825)Sb_(0.07)Ta_(0.0475))O_(3)(KNLNST)piezoelectric ceramics are synthesized by the conventional solid-state reaction method.The sintering temperature and poling temper...Lead-free(K_(0.4425)Na_(0.52)Li_(0.0375))(Nb_(0.8825)Sb_(0.07)Ta_(0.0475))O_(3)(KNLNST)piezoelectric ceramics are synthesized by the conventional solid-state reaction method.The sintering temperature and poling temperature dependence of ceramic properties are investigated.Previous studies have shown that variation of sintering temperature can cause phase transition,similar to the morphotropic phase boundary(MPB)behavior induced by composition changes in Pb(Zr,Ti)O_(3)(PZT).And the best piezoelectric performance can be obtained near the phase-transition sintering temperature.In this research,phase transition induced by sintering temperature cannot be detected and excellent piezoelectric properties can still be obtained.The sintering temperature of the largest piezoelectric coefficient of such composition is lower than that of the highest density,which is considered in composition segregation as a result of intensified volatilization of alkali metal oxides.Combined with the effect of poling temperature,the peak values of the piezoelectric properties are d_(33)=313 pC/N,k_(p)=47%,ε_(r)=1825,tanδd=0.024,T_(o-t)=88℃,and TC=274℃.展开更多
基金Project(10474077) supported by the National Natural Science Foundation of China Project(2002CB613304) supported by the National Basic Research Program of China
文摘The lead-free piezoelectric ceramics (K0.5Na0.5)NbO3 (abbreviated as KNN) with the relative density of 97.6% were synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics was analyzed. The results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of poling conditions on the piezoelectric properties of KNN ceramics was investigated. The results show that the piezoelectric constant d33 and electromechanical coupling factor kp increase with poling field, poling temperature and poling time increasing, then decrease because of electric broken. Take into account of poling conditions and piezoelectric properties of pure KNN ceramics, the optimum poling conditions for pure KNN ceramics are poling field of 4 kV/mm, poling temperature of 140℃and poling time of 20-25 min.
基金financially supported by National Nature Science Foundation of China(No.50872080)Shanghai Special Foundation of Nanotechnology(No.1052nm07300)+2 种基金Shanghai Education Development Foundation(No.08SG41)Shanghai Leading Academic Disciplines(No.S30107)Innovational Foundation of Shanghai University
文摘Piezoelectric ceramics of 0.6(Bi0.9La0.1)FeO3-0.4Pb(Ti1-xMnx)O3 (BLF-PTM) for x=0, 0.01, 0.02, and 0.03 were prepared by sol-gel process combined with a solid-state reaction method. The tan? for BLF-PTM of x=0.01 is just 0.006 at 1 kHz, drastically decreasing by using Mn dopants. The TC increases to 490 ℃ for BLF-PTM of x=0.02. Furthermore, Mn modification effectively enhances the poling state and the piezoelectric properties of BLF-PTM. The kp, Qm, d33, and g33 of 0.34, 403, and 124 pC1·N-1 and 37×10-3 Vm·N-1 are achieved for BLF-PTM of x=0.01. The results indicate that Mn modified BLF-PTM is a competitive high power and high temperature piezoelectric material with excellent piezoelectric properties.
基金financially supported by the National Key Research and Development Program of China(No.2018YFC0308603)the Pilot Technology for Chinese Academy of Sciences(No.XDA2203003)the National Natural Science Foundation of China(Nos.51972321 and 51879269)。
文摘High piezoelectric properties and superior thermal stability are both important indicators of piezoelectric ceramics serving at high temperature.However,since these properties are usually mutually exclusive,high performance and superior thermal stability are hard to achieve simultaneously.Here we report that a high piezoelectricity(d_(33)∼562 pC/N)and superior thermal stability(the variation is within 7%from 20 to 330℃)were both achieved in 0.4 mol%ZnO-doped 0.02Pb(Sb_(1/2)Nb_(1/2))-0.51PbZrO_(3)-0.47PbTiO_(3) by high-temperature poling.Compared with traditional poling method,high-temperature poling method forms a small-sized and highly oriented domain structure,which can effectively improve the piezoelectric and dielectric properties of piezoelectric ceramics.At the same time,the enhanced pinning effect of defect ions and stabilized domain structure due to high-temperature poling also contribute to the superior temperature stability of the piezoelectric and dielectric properties.This work provides an effective method for designing piezoelectric materials with high performance and good temperature stability for high temperature sensor applications.
文摘The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs poled at high voltage(HV,5 kV_(rms)/cm)occasionally showed large fluctuations and low opposite values of piezoelectric coefficient(d_(33)=±1370 pC/N)in one plate.This revealed spuriousmode vibrations(SMV)of impedance spectrum.However,after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage(LV,3.5 kV_(rms)/cm),the d_(33) enhanced to be 1720 pC/N(+26%)and did not exhibit large fluctuation or opposite values in one plate any more.The impedance spectrum became clean and the abnormal SMV disappeared.We proposed four possible mechanisms of the SMV,and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs.This study will be useful to realize a high d_(33) and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.
基金This study was supported by the National Natural Science Foundation of China(No.51172108)the project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Lead-free(K_(0.4425)Na_(0.52)Li_(0.0375))(Nb_(0.8825)Sb_(0.07)Ta_(0.0475))O_(3)(KNLNST)piezoelectric ceramics are synthesized by the conventional solid-state reaction method.The sintering temperature and poling temperature dependence of ceramic properties are investigated.Previous studies have shown that variation of sintering temperature can cause phase transition,similar to the morphotropic phase boundary(MPB)behavior induced by composition changes in Pb(Zr,Ti)O_(3)(PZT).And the best piezoelectric performance can be obtained near the phase-transition sintering temperature.In this research,phase transition induced by sintering temperature cannot be detected and excellent piezoelectric properties can still be obtained.The sintering temperature of the largest piezoelectric coefficient of such composition is lower than that of the highest density,which is considered in composition segregation as a result of intensified volatilization of alkali metal oxides.Combined with the effect of poling temperature,the peak values of the piezoelectric properties are d_(33)=313 pC/N,k_(p)=47%,ε_(r)=1825,tanδd=0.024,T_(o-t)=88℃,and TC=274℃.
