High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adop...High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.展开更多
BiFeO_(3)-BaTiO_(3)(BF-BT)lead-free piezoelectric ceramics have high piezoelectricity and high Curie temperature(T_(C)),but the mixed-valence Fe ions and Bi^(3+)volatilization would promote the formation of Bi_(25)FeO...BiFeO_(3)-BaTiO_(3)(BF-BT)lead-free piezoelectric ceramics have high piezoelectricity and high Curie temperature(T_(C)),but the mixed-valence Fe ions and Bi^(3+)volatilization would promote the formation of Bi_(25)FeO_(40)/Bi_(2)Fe_(4)O_9 and oxygen vacancy,which greatly degrade the insulation properties required for polarization.In this study,it was found that the modification of BiAlO_(3)(BA)in BF-BT ceramics could effectively solve these problems,reducing the leakage current to 1×10^(-9)A·cm^(-2)and transiting the space charge-limited conduction to ohmic conduction.Because of the enhanced insulation properties and appropriate rhombohedral-pseudocubic phase ratio(C_R/C_(PC)),BF-BT-xBA ceramics in an optimized composition obtain enhanced piezoelectric performance:piezoelectric charge coefficient(d_(33))=196 pC·N^(-1),planar electromechanical coupling coefficient(k_(p))=31.1%,T_(C)=487℃and depolarization temperature(T_d)=250°C;unipolar strain(S_(uni))=0.17%and piezoelectric strain coefficient(d_(33)^(*))=335 pm·V^(-1)at 100℃.Especially,d_(33)exceeds 283 pC·N^(-1)at 233℃and d_(33)^(*)is 335 pm·V^(-1)at100℃,showing an excellent high-temperature piezoelectricity and high depolarization temperature.The results are attributed to the domain structure of rhombohedral-pseudocubic phase coexistence and its high-temperature switching behavior.This work provides a feasible and effective approach to improve the high temperature piezoelectric properties of BF-BT-xBA ceramics,making them more suitable for high temperature applications.展开更多
Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaT...Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaTiO_(3)ceramics,an excellent piezoelectric constant(d33)of 325 pC/N was achieved by applying a novel poling method(AC-biasþDC-bias)with a high TC of 455℃.In addition,an ultrahigh normalized piezoelectric strain(d33*¼Smax/Emax)of 808 pm/V was obtained at the normal/typical and relaxor-ferroelectrics phase boundary simultaneously with good thermal stability(Dd33*(T)z 20%)in the temperature range of 25e125℃.The piezoelectric force microscopy results show the domain miniaturization from micro to nanoscale/polar nano-regions due to local structure heterogeneity caused by Nd doping.The mechanism for the giant piezoelectric strain is attributed to the thermal quenching,nano-domains,and reverse switching of the short-range order to the long-range order under the applied electric field.The strategic design of domain engineering and a proposed model for the high piezoelectricity is successfully supported by the phenomenological relation and Gibbs free energy profile.In this work,a new lead-free single-element modified BiFeO_(3)-BaTiO_(3)ceramics was developed by applying a synergistic approach of domain engineering and phase boundary for the high-temperature piezoelectric performance.展开更多
BiFeO_(3)–BaTiO_(3)(BF–BT)based piezoelectric ceramics are a kind of high-temperature lead-free piezoelectric ceramics with great development prospects due to their high Curie temperature(TC)and excellent electrical...BiFeO_(3)–BaTiO_(3)(BF–BT)based piezoelectric ceramics are a kind of high-temperature lead-free piezoelectric ceramics with great development prospects due to their high Curie temperature(TC)and excellent electrical properties.However,large leakage current limits their performance improvement and practical applications.In this work,direct current(DC)test,alternating current(AC)impedance,and Hall tests were used to investigate conduction mechanisms of 0.75BiFeO_(3)–0.25BaTiO_(3)ceramics over a wide temperature range.In the range of room temperature(RT)−150℃,ohmic conduction plays a predominant effect,and the main carriers are p-type holes with the activation energy(Ea)of 0.51 eV.When T>200℃,the Ea value calculated from the AC impedance and Hall data is 1.03 eV with oxygen vacancies as a cause of high conductivity.The diffusion behavior of thermally activated oxygen vacancies is affected by crystal symmetry,oxygen vacancy concentration,and distribution,dominating internal conduction mechanism.Deciphering the conduction mechanisms over the three temperature ranges would pave the way for further improving the insulation and electrical properties of BiFeO_(3)–BaTiO_(3)ceramics.展开更多
It is well-known that the performance of BiFeO3eBaTiO3(BF-BT)ceramics is sensitive to composition,calcining and sintering temperature(Tcal and Tsint)due to the formation of Bi25FeO39 and/or Bi2Fe4O9 impurities and/or ...It is well-known that the performance of BiFeO3eBaTiO3(BF-BT)ceramics is sensitive to composition,calcining and sintering temperature(Tcal and Tsint)due to the formation of Bi25FeO39 and/or Bi2Fe4O9 impurities and/or the volatilization of Bi_(2)O_(3).We report remarkably stable electrical properties over the range of0.03≤x≤0.05 and 930℃≤Tsint≤970C in 0.7Bi(1þx)FeO_(3)-0.3BaTiO_(3)ceramics prepared by one-step process.This method avoids the thermodynamically unstable region of BiFeO_(3)and prevents the formation of Bi25FeO39 and/or Bi_(2)Fe_(4)O_(9)impurities even when the addition of a-Bi_(2)O_(3)raw material is intentionally deficient or rich to make off-stoichiometric BF-BT,thus greatly improving the robustness of compositional and processing.Rhombohedral-pseudocubic phase coexists in all ceramics,and their CR/CPC fraction are 48.0/52.0e50.6/49.4 and 55.9/44.1e56.6/43.4 when x increases from0.05≤x≤0 to 0.01≤x≤0.05.The stable electrical properties of d33¼180e205 pC/N,Pr¼17.9e23.8 mC/cm^(2),and TC¼485e518℃are achieved.The maximum d_(33T)/d_(33RT)of BF-BT is twice that of soft PZT,superior to most the-state-of-art lead-free ceramics.Our results provide a synthesis strategy for designing high performance piezoelectric materials with good stability and easy industrialization.展开更多
BiFeO_(3)-BaTiO_(3)is a promising lead-free piezoelectric ceramic,exhibiting high Curie temperature and superior electrochemical characteristics.In this work,e_(1-x)TBiFeO_(3)-xBaTiO_(3)(BF-xBT,x=0.26,0.28,0.30,0.32,0...BiFeO_(3)-BaTiO_(3)is a promising lead-free piezoelectric ceramic,exhibiting high Curie temperature and superior electrochemical characteristics.In this work,e_(1-x)TBiFeO_(3)-xBaTiO_(3)(BF-xBT,x=0.26,0.28,0.30,0.32,0.34,0.36)ceramics were fabricated using the conventional solid-state reaction method through precise composition control.Multiple characterization techniques,including X-ray powder diffraction(XRD),scanning electron microscope(SEM),and electrical property testing systems,were applied to systematically examine the crystallographic structure,microstructure,as well as the dielectric,ferroelectric and piezoelectric properties of the BF-xBT ceramics.The XRD results confirm that all compositions exhibit a typical perovskite structure,transitioning from a single rhombohedral phase to a rhombohedral-cubic phase mixture as the BT content increases.SEM shows apparent core-shell microstructures in the ceramics.Notably,the results demonstrated that the BF-0.30BT ceramic exhibits the maximum piezoelectric constant(d_(33))-217 pC/N,while the BF-0.34BT ceramic displays the maximum converse piezoelectric constant(d_(33)^(*))-323 pm/V,which highlights the suitability of BF-BT ceramics for high-performance piezoelectric applications.展开更多
Lead-based electroceramics such as Pb(Zr.Ti)O_(3)(PZT)and its derivatives have excellent piezoelectric,pyroelectric and energy storage properties and can be used in a wide range of applications.Potential lead-free rep...Lead-based electroceramics such as Pb(Zr.Ti)O_(3)(PZT)and its derivatives have excellent piezoelectric,pyroelectric and energy storage properties and can be used in a wide range of applications.Potential lead-free replacements for PZT such as potassium sodium niobate(KNN)and sodium bismuth titanate(NBT)have a much more limited range of useful properties and have been optimized primarily for piezoelectric applications.Here,we review the initial results on a new generation of lead-free electroceramics based on BiFeO_(3)-BaTiO_(3)(BF-BT)highlighting the essential crystal chemistry that permits a wide range of functional properties.We demonstrate that with the appropriate dopants and heat treatment,BF-BT can be used to fabricate commercially viable ceramics for applications,ranging from sensors,multilayer actuators,capacitors and high-density energy storage devices.We also assess the potential of BF-BT-based ceramics for electrocaloric and pyroelectric applications.展开更多
基金the National Key Research and Development Program of China(Grant No.2022YFB3807404)the Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents (Grant No. BX2021377 ).
文摘High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.
基金financially supported by the National Natural Science Foundation of China (Nos.52072028 and52032007)National Key Research and Development Program (No.2022YFB3807400)。
文摘BiFeO_(3)-BaTiO_(3)(BF-BT)lead-free piezoelectric ceramics have high piezoelectricity and high Curie temperature(T_(C)),but the mixed-valence Fe ions and Bi^(3+)volatilization would promote the formation of Bi_(25)FeO_(40)/Bi_(2)Fe_(4)O_9 and oxygen vacancy,which greatly degrade the insulation properties required for polarization.In this study,it was found that the modification of BiAlO_(3)(BA)in BF-BT ceramics could effectively solve these problems,reducing the leakage current to 1×10^(-9)A·cm^(-2)and transiting the space charge-limited conduction to ohmic conduction.Because of the enhanced insulation properties and appropriate rhombohedral-pseudocubic phase ratio(C_R/C_(PC)),BF-BT-xBA ceramics in an optimized composition obtain enhanced piezoelectric performance:piezoelectric charge coefficient(d_(33))=196 pC·N^(-1),planar electromechanical coupling coefficient(k_(p))=31.1%,T_(C)=487℃and depolarization temperature(T_d)=250°C;unipolar strain(S_(uni))=0.17%and piezoelectric strain coefficient(d_(33)^(*))=335 pm·V^(-1)at 100℃.Especially,d_(33)exceeds 283 pC·N^(-1)at 233℃and d_(33)^(*)is 335 pm·V^(-1)at100℃,showing an excellent high-temperature piezoelectricity and high depolarization temperature.The results are attributed to the domain structure of rhombohedral-pseudocubic phase coexistence and its high-temperature switching behavior.This work provides a feasible and effective approach to improve the high temperature piezoelectric properties of BF-BT-xBA ceramics,making them more suitable for high temperature applications.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3807404),Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)and the State Key Laboratory of Powder Metallurgy.Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents(Grant No.BX2021377).
文摘Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaTiO_(3)ceramics,an excellent piezoelectric constant(d33)of 325 pC/N was achieved by applying a novel poling method(AC-biasþDC-bias)with a high TC of 455℃.In addition,an ultrahigh normalized piezoelectric strain(d33*¼Smax/Emax)of 808 pm/V was obtained at the normal/typical and relaxor-ferroelectrics phase boundary simultaneously with good thermal stability(Dd33*(T)z 20%)in the temperature range of 25e125℃.The piezoelectric force microscopy results show the domain miniaturization from micro to nanoscale/polar nano-regions due to local structure heterogeneity caused by Nd doping.The mechanism for the giant piezoelectric strain is attributed to the thermal quenching,nano-domains,and reverse switching of the short-range order to the long-range order under the applied electric field.The strategic design of domain engineering and a proposed model for the high piezoelectricity is successfully supported by the phenomenological relation and Gibbs free energy profile.In this work,a new lead-free single-element modified BiFeO_(3)-BaTiO_(3)ceramics was developed by applying a synergistic approach of domain engineering and phase boundary for the high-temperature piezoelectric performance.
基金supported by the National Natural Science Foundation of China(Nos.52072028,52032007)National Key R&D Program of China(No.2022YFB3807400).
文摘BiFeO_(3)–BaTiO_(3)(BF–BT)based piezoelectric ceramics are a kind of high-temperature lead-free piezoelectric ceramics with great development prospects due to their high Curie temperature(TC)and excellent electrical properties.However,large leakage current limits their performance improvement and practical applications.In this work,direct current(DC)test,alternating current(AC)impedance,and Hall tests were used to investigate conduction mechanisms of 0.75BiFeO_(3)–0.25BaTiO_(3)ceramics over a wide temperature range.In the range of room temperature(RT)−150℃,ohmic conduction plays a predominant effect,and the main carriers are p-type holes with the activation energy(Ea)of 0.51 eV.When T>200℃,the Ea value calculated from the AC impedance and Hall data is 1.03 eV with oxygen vacancies as a cause of high conductivity.The diffusion behavior of thermally activated oxygen vacancies is affected by crystal symmetry,oxygen vacancy concentration,and distribution,dominating internal conduction mechanism.Deciphering the conduction mechanisms over the three temperature ranges would pave the way for further improving the insulation and electrical properties of BiFeO_(3)–BaTiO_(3)ceramics.
基金supported by the National Natural Science Foundation of China(52072028 and 52032007).
文摘It is well-known that the performance of BiFeO3eBaTiO3(BF-BT)ceramics is sensitive to composition,calcining and sintering temperature(Tcal and Tsint)due to the formation of Bi25FeO39 and/or Bi2Fe4O9 impurities and/or the volatilization of Bi_(2)O_(3).We report remarkably stable electrical properties over the range of0.03≤x≤0.05 and 930℃≤Tsint≤970C in 0.7Bi(1þx)FeO_(3)-0.3BaTiO_(3)ceramics prepared by one-step process.This method avoids the thermodynamically unstable region of BiFeO_(3)and prevents the formation of Bi25FeO39 and/or Bi_(2)Fe_(4)O_(9)impurities even when the addition of a-Bi_(2)O_(3)raw material is intentionally deficient or rich to make off-stoichiometric BF-BT,thus greatly improving the robustness of compositional and processing.Rhombohedral-pseudocubic phase coexists in all ceramics,and their CR/CPC fraction are 48.0/52.0e50.6/49.4 and 55.9/44.1e56.6/43.4 when x increases from0.05≤x≤0 to 0.01≤x≤0.05.The stable electrical properties of d33¼180e205 pC/N,Pr¼17.9e23.8 mC/cm^(2),and TC¼485e518℃are achieved.The maximum d_(33T)/d_(33RT)of BF-BT is twice that of soft PZT,superior to most the-state-of-art lead-free ceramics.Our results provide a synthesis strategy for designing high performance piezoelectric materials with good stability and easy industrialization.
基金supported by the Science,Technology and Innovation Committee of Shenzhen Municipality(Grant Nos.:JCYJ20220531095802005 and RCBS20210706092341001).
文摘BiFeO_(3)-BaTiO_(3)is a promising lead-free piezoelectric ceramic,exhibiting high Curie temperature and superior electrochemical characteristics.In this work,e_(1-x)TBiFeO_(3)-xBaTiO_(3)(BF-xBT,x=0.26,0.28,0.30,0.32,0.34,0.36)ceramics were fabricated using the conventional solid-state reaction method through precise composition control.Multiple characterization techniques,including X-ray powder diffraction(XRD),scanning electron microscope(SEM),and electrical property testing systems,were applied to systematically examine the crystallographic structure,microstructure,as well as the dielectric,ferroelectric and piezoelectric properties of the BF-xBT ceramics.The XRD results confirm that all compositions exhibit a typical perovskite structure,transitioning from a single rhombohedral phase to a rhombohedral-cubic phase mixture as the BT content increases.SEM shows apparent core-shell microstructures in the ceramics.Notably,the results demonstrated that the BF-0.30BT ceramic exhibits the maximum piezoelectric constant(d_(33))-217 pC/N,while the BF-0.34BT ceramic displays the maximum converse piezoelectric constant(d_(33)^(*))-323 pm/V,which highlights the suitability of BF-BT ceramics for high-performance piezoelectric applications.
基金supported by the Engineering and Physical Sciences Research Council(EP/L017563/1 and EP/N010493/1)and National Natural Science Foundation of China(51602060 and 51402005).D.Wang,G.Wang and S.Murakami contributed equally to this work and should be considered as co-first authors.
文摘Lead-based electroceramics such as Pb(Zr.Ti)O_(3)(PZT)and its derivatives have excellent piezoelectric,pyroelectric and energy storage properties and can be used in a wide range of applications.Potential lead-free replacements for PZT such as potassium sodium niobate(KNN)and sodium bismuth titanate(NBT)have a much more limited range of useful properties and have been optimized primarily for piezoelectric applications.Here,we review the initial results on a new generation of lead-free electroceramics based on BiFeO_(3)-BaTiO_(3)(BF-BT)highlighting the essential crystal chemistry that permits a wide range of functional properties.We demonstrate that with the appropriate dopants and heat treatment,BF-BT can be used to fabricate commercially viable ceramics for applications,ranging from sensors,multilayer actuators,capacitors and high-density energy storage devices.We also assess the potential of BF-BT-based ceramics for electrocaloric and pyroelectric applications.
基金R&D Projects in Key Fields of Guangdong Province (2020B0109380001, 2019B040403004, 2019B040403006)Science and Technology Planning Project of Guangxi Zhuang Autonomous Region (AA18118034)+1 种基金National Natural Science Foundation of China (51577070, U1601208)Science and Technology Program of Guangzhou (201704030095)。
