The development of high-strain piezoelectric materials has presented a longstanding challenge,particularly in the development of high-strain polycrystalline lead-free piezoelectric thin films.In this work,we present a...The development of high-strain piezoelectric materials has presented a longstanding challenge,particularly in the development of high-strain polycrystalline lead-free piezoelectric thin films.In this work,we present a strategy for customizing the electrostrain in lead-free thin films through phase transition engineering.In this study,we achieved a high recoverable electrostrain in a Bi_(1/2)Na_(1/2)TiO_(3)–BiAlO_(3)(BNT–BA)film.To accomplish this,ferroelectric BNT and BNT–BA films with identical thicknesses of 500 nm were fabricated on Pt(111)/TiO_(2)/SiO_(2)/Si(100)substrates via a sol-gel method.Compared with the BNT film,the BNT–BA film exhibited a greater polarization response and superior field strength endurance,maintaining the energy storage density beyond the breakdown field strength of the BNT.The BNT–BA film demonstrated a large unipolar strain of S=0.43%with a normalized strain(maximum strain/maximum applied electric field(S_(max)/E_(max)))of 203 pm/V,followed by an effective transverse piezoelectric coefficient(e∗31,f)of~2.48 C/m^(2),which was more than two times greater than the value obtained for BNT(i.e.,maximum strain/maximum applied electric field(S_(max)/E_(max))=72 pm/V and e^(∗)_(31,f)of~1.09 C/m^(2)).This high strain response in the BNT–BA film can be attributed to the electric-field-induced phase transition of the mixed(i.e.,cubic and rhombohedral)phases into rhombohedral and tetragonal phases(mainly the rhombohedral structure),which recover back to the original state when the electric field is removed.These findings suggest new pathways for achieving significant strain levels via alternative mechanisms,potentially enhancing the effectiveness and expanding the applications of piezoelectric materials.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
Covalent organic frameworks(COFs)have emerged as auspicious porous adsorbents for radioiodine capture.However,their conventional solvothermal synthesis demands multiday synthetic times and anaerobic conditions,largely...Covalent organic frameworks(COFs)have emerged as auspicious porous adsorbents for radioiodine capture.However,their conventional solvothermal synthesis demands multiday synthetic times and anaerobic conditions,largely hampering their practical use.To tackle these challenges,we present a facile microwave-assisted synthesis of 2D imine-linked COFs,Mw-TFB-BD-X,(X=−CH_(3) and−OCH_(3))under air within just 1 h.The resultant COFs possessed higher crystallinity,better yields,and more uniform morphology than their solvothermal counterparts.Remarkably,Mw-TFB-BD-CH_(3) and Mw-TFB-BDOCH_(3) exhibited exceptional iodine adsorption capacities of 7.83 g g^(−1) and 7.05 g g^(−1),respectively,placing them among the bestperforming COF adsorbents for static iodine vapor capture.Moreover,Mw-TFB-BD-CH_(3) and Mw-TFB-BD-OCH_(3) can be reused 5 times with no apparent loss in the adsorption capacity.The exceptionally high iodine adsorption capacities and excellent reusability of COFs were mainly attributed to their uniform spherical morphology and enhanced chemical stability due to the in-built electron-donating groups,despite their low surface areas.This work establishes a benchmark for developing advanced iodine adsorbents that combine fast kinetics,high capacity,excellent reusability,and facile rapid synthesis,a set of appealing features that remain challenging to merge in COF adsorbents so far.展开更多
Three different series of lead-free ceramics,i.e.,(1-y)Bi1.03(1_x)LaxFeO_(3)-yBaTiO_(3)(y=0.27,x=0.00-0.12),(y=0.30,x=0.00-0.10),and(y=0.33,x=0.00-0.08)are prepared via a conventional solid-state reaction with water q...Three different series of lead-free ceramics,i.e.,(1-y)Bi1.03(1_x)LaxFeO_(3)-yBaTiO_(3)(y=0.27,x=0.00-0.12),(y=0.30,x=0.00-0.10),and(y=0.33,x=0.00-0.08)are prepared via a conventional solid-state reaction with water quenching.From X-ray diffraction and electrical property measurements,two morphotropic phase boundaries(MPBs)are discovered in all three ceramic systems.The first MPB(MPB-Ⅰ)appeared between rhombohedral and tetragonal phases,whereas the second MPB(MPB-Ⅱ)appeared between tetragonal and cubic-like phases.The highest direct piezoelectric coefficients(d_(33)=201,274,and 268 pC/N)are mainly attributed to the typical MPB-I of the rhombohedral and tetragonal phases.However,the highest converse piezoelectric coefficients(d_(33*)=490,500,and 570 pm/V with Curie temperature>330℃)are obtained for compositions near to the MPB-II.A significant enhancement in the dielectric constant at low temperature is associated with the local structural heterogeneity by La^(3+)doping,which serves as an origin for a high piezoelectric strain response.Based on the crystal structure as well as on the dielectric,ferroelectric,and piezoelectric properties,a phase diagram is constructed for La-doped BiFeO3-BaTiO3 ceramics.This phase diagram reveals the relationship between piezoelectric performance and crystal structure.展开更多
基金support of the Priority Research Centers Program and the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(Nos.NRF2019R1A6A1A11053838 and RS-2023-00245221)Aman Ullah acknowledges the support of the Higher Education Commission of Islamabad,Pakistan,under the National Research Program for Universities-NRPU(20-17573/NRPU/R&D/HEC/2021)Muhammad Sheeraz acknowledges support from the Basic Science Research Program through NRF(No.RS-2023-00249613).
文摘The development of high-strain piezoelectric materials has presented a longstanding challenge,particularly in the development of high-strain polycrystalline lead-free piezoelectric thin films.In this work,we present a strategy for customizing the electrostrain in lead-free thin films through phase transition engineering.In this study,we achieved a high recoverable electrostrain in a Bi_(1/2)Na_(1/2)TiO_(3)–BiAlO_(3)(BNT–BA)film.To accomplish this,ferroelectric BNT and BNT–BA films with identical thicknesses of 500 nm were fabricated on Pt(111)/TiO_(2)/SiO_(2)/Si(100)substrates via a sol-gel method.Compared with the BNT film,the BNT–BA film exhibited a greater polarization response and superior field strength endurance,maintaining the energy storage density beyond the breakdown field strength of the BNT.The BNT–BA film demonstrated a large unipolar strain of S=0.43%with a normalized strain(maximum strain/maximum applied electric field(S_(max)/E_(max)))of 203 pm/V,followed by an effective transverse piezoelectric coefficient(e∗31,f)of~2.48 C/m^(2),which was more than two times greater than the value obtained for BNT(i.e.,maximum strain/maximum applied electric field(S_(max)/E_(max))=72 pm/V and e^(∗)_(31,f)of~1.09 C/m^(2)).This high strain response in the BNT–BA film can be attributed to the electric-field-induced phase transition of the mixed(i.e.,cubic and rhombohedral)phases into rhombohedral and tetragonal phases(mainly the rhombohedral structure),which recover back to the original state when the electric field is removed.These findings suggest new pathways for achieving significant strain levels via alternative mechanisms,potentially enhancing the effectiveness and expanding the applications of piezoelectric materials.
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 U.S.Department of Energy Office of Science Early Career Research Program(DESC0022000)the National Science Foundation HBCU-UPRIA program(no.2100360)+2 种基金the U.S.Department of Defense,the Office of Naval Research(no:N00014-20-1-2523)supported by the Office of Science,Office of Basic Energy Sciences,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231the support from Qassim University.S.C.is grateful for the support from the National Natural Science Foundation of China(no.22171092).
文摘Covalent organic frameworks(COFs)have emerged as auspicious porous adsorbents for radioiodine capture.However,their conventional solvothermal synthesis demands multiday synthetic times and anaerobic conditions,largely hampering their practical use.To tackle these challenges,we present a facile microwave-assisted synthesis of 2D imine-linked COFs,Mw-TFB-BD-X,(X=−CH_(3) and−OCH_(3))under air within just 1 h.The resultant COFs possessed higher crystallinity,better yields,and more uniform morphology than their solvothermal counterparts.Remarkably,Mw-TFB-BD-CH_(3) and Mw-TFB-BDOCH_(3) exhibited exceptional iodine adsorption capacities of 7.83 g g^(−1) and 7.05 g g^(−1),respectively,placing them among the bestperforming COF adsorbents for static iodine vapor capture.Moreover,Mw-TFB-BD-CH_(3) and Mw-TFB-BD-OCH_(3) can be reused 5 times with no apparent loss in the adsorption capacity.The exceptionally high iodine adsorption capacities and excellent reusability of COFs were mainly attributed to their uniform spherical morphology and enhanced chemical stability due to the in-built electron-donating groups,despite their low surface areas.This work establishes a benchmark for developing advanced iodine adsorbents that combine fast kinetics,high capacity,excellent reusability,and facile rapid synthesis,a set of appealing features that remain challenging to merge in COF adsorbents so far.
基金supported by the Technology Development Program of Ministry of Small,medium enterprises and Startups(MSS),Korea[S2762001,S2731048]the National Research Foundation of Korea(NRF)grants(2017R1I1A1A01059072,2019R1I1A1A01059072,2019R1F1A1059292)a grant funded by the Ministry of Science and ICT(MIST),Korea(No.2019-0254).
文摘Three different series of lead-free ceramics,i.e.,(1-y)Bi1.03(1_x)LaxFeO_(3)-yBaTiO_(3)(y=0.27,x=0.00-0.12),(y=0.30,x=0.00-0.10),and(y=0.33,x=0.00-0.08)are prepared via a conventional solid-state reaction with water quenching.From X-ray diffraction and electrical property measurements,two morphotropic phase boundaries(MPBs)are discovered in all three ceramic systems.The first MPB(MPB-Ⅰ)appeared between rhombohedral and tetragonal phases,whereas the second MPB(MPB-Ⅱ)appeared between tetragonal and cubic-like phases.The highest direct piezoelectric coefficients(d_(33)=201,274,and 268 pC/N)are mainly attributed to the typical MPB-I of the rhombohedral and tetragonal phases.However,the highest converse piezoelectric coefficients(d_(33*)=490,500,and 570 pm/V with Curie temperature>330℃)are obtained for compositions near to the MPB-II.A significant enhancement in the dielectric constant at low temperature is associated with the local structural heterogeneity by La^(3+)doping,which serves as an origin for a high piezoelectric strain response.Based on the crystal structure as well as on the dielectric,ferroelectric,and piezoelectric properties,a phase diagram is constructed for La-doped BiFeO3-BaTiO3 ceramics.This phase diagram reveals the relationship between piezoelectric performance and crystal structure.
