Domain size and charge defects affecting the polarization switching of antiferroelectric domains

The switching behavior of antiferroelectric domain structures under the applied electric field is not fully understood.In this work,by using the phase field simulation,we have studied the polarization switching property of antiferroelectric domains.Our results indicate that the ferroelectric domains nucleate preferably at the boundaries of the antiferroelectric domains,and antiferroelectrics with larger initial domain sizes possess a higher coercive electric field as demonstrated by hysteresis loops.Moreover,we introduce charge defects into the sample and numerically investigate their influence.It is also shown that charge defects can induce local ferroelectric domains,which could suppress the saturation polarization and narrow the enclosed area of the hysteresis loop.Our results give insights into understanding the antiferroelectric phase transformation and optimizing the energy storage property in experiments.

High piezoelectricity and low strain hysteresis in PMN-PT-based piezoelectric ceramics

High piezoelectric properties and low strain hysteresis(H)are both equally necessary for practical applications in precisely controlled piezoelectric devices and systems.Unlike most of previous reports,where enhanced piezoelectric performance is typically accompanied by large hysteresis in lead-/lead-free-based ceramics,in this work,we report a reconstructed relaxor ferroelectric composition in 0.68Pb(Mg_(1/3)Nb_(2/3))O3-0.32PbTiO_(3)(0.68PMN-0.32PT)ceramics through the introduction of(Bi_(0.5)Na_(0.5))ZrO(BNZ)to simultaneously achieve low strain hysteresis(~7.68%),superior piezoelectricity(~1040 pC·N^(-l)),and an electric field induced strain of 0.175%.Our work not only paves the way to simultaneously large piezoelectricity and negligible strain hysteresis in ceramic systems,but also lays the foundation for the further development of novel functional materials.

A review of flexible perovskite oxide ferroelectric films and their application

Many perovskite oxide ferroelectrics(e.g.PbZr_(1-x)Ti_(x)O_(3),BaTiO_(3),LiNbO_(3))are born with multitudinous robust performances and have been widely used in sensors,actuators,surface acoustic wave devices,and memories et al.However,their hardness,brittleness and harsh synthesis conditions(i.e.high temperature and oxygen ambience)restrain their application into flexible electronic devices which are significant components among the three pillars of modern society development,i.e.energy,information and materials.Here we review the preparation of flexible devices based on these oxide ferroelectrics,including transferring these freestanding films to flexible substrates after separating ferroelectric oxide films from the hard substrates,such as Si and SrTiO_(3) crystals,and also direct fabrication methods without transferring process.Subsequently,we summarize three kinds of representative flexible devices,i.e.flexible ferroelectric memories,sensors and generators.These inorganic electronics not only show excellent electric properties competitive with those corresponding electronics on hard substrates but also exhibit good flexibility similar to many organic flexible electronics.

Toward artificial intelligent self-cooling electronic skins:Large electrocaloric effect in all-inorganic flexible thin films at room temperature

Intelligent robots have assisted mankind in achieving and operating thousands of functions,especially with the arrival of the artificial intelligent.However,heat dissipation and thermal management in the intelligent robots remain big challenges,which limit their miniaturization and performance.Electrocaloric(EC)materials,which exhibit temperature change in response to the application or withdrawal of an electric field,open a new strategy for cooling technology and have gained a flurry of research interest in recent years.Toward artificial intelligent self-cooling electronic skins,large-scale flexible materials with high EC effect near room temperature are in demand.Here,we report a large room temperature EC effect in flexible Pb_(0.82)Ba_(0.08)La_(0.1)Zr0.9Ti_(0.1)O_(3)(PBLZT)inorganic thin films via a transfer-free cost-effective sol-gel process,assisted by unique two-dimensional mica substrates.The maximum adiabatic temperature change and isothermal entropy change of the flexible PBLZT thin films reach to 22.5 K and 25.9 J K^(-1) kg^(-1) at room temperature.In particular,the flexible PBLZT thin films exhibit a stable EC effect both under bending state and after bending for 20000 times.Our flexible EC materials offer an alternative strategy to the development of cooling technologies for both artificial intelligent robots and personal wearable cooling devices.

Bio-inspired flexible vibration visualization sensor based on piezo-electrochromic effect

Monitoring structural vibration can provide quantitative information for both structural health evaluations and early-warning maintenance.The most classic vibration-based structural health monitoring is equipped with piezoelectric accelerometers,which is expensive and inconvenient due to cumbersome and time-consuming sensor installation and high power-consumptive data acquisition systems.One other main challenge with these systems is the inherent limitations for multi-point monitoring in critical elements with curvature due to their non-conformability.Here,inspired by the chameleon,we report a cost-effective,flexible and conformal,self-powered vibration sensor based on elasto-electro-chemical synergistic effect of piezoelectricity and electrochromism.The sensor can provide not only in-situ visualization,but also ex-situ recording of structural vibration due to the non-volatile color memory effect of electrochromism.The passive sensor system is composed of two distinct electronic components d ternary Pb(In1/2Nb1/2)O_(3)ePb(Mg1/3Nb2/3)O_(3)ePbTiO_(3)piezoelectric single crystal ribbon sensors and a solid-state tungsten trioxide electrochromic indicator driven by vibration-induced voltage generated by the piezoelectric ribbons.The proposed piezo-electrochromic based passive non-volatile visualization sensor may find diverse applications in structural health monitoring,smart wallpapers,and medical injury rehabilitation.

Eu-doped K_(0.5)Na_(0.5)NbO_(3)-(Ba,Sr)TiO_(3):A novel lead-free luminescent ferroelectric transparent ceramic with reversible photochromism

Photochromic(PC)luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories,optical switches and bio-imaging.However,those materials are basically opaque.In this work,we prepared a PC luminescent K_(0.5)Na_(0.5)NbO_(3)-(Ba,Sr)TiO_(3)-based ferroelectric transparent ceramic by modifying with Eu^(3+),Ba^(2+,)Ti^(4+)and Sr^(2+),which not only have good optical transmittances(-60%at 900 nm),moderate ferroelectric properties and down-conversion photo-luminescence(PL)properties,but also exhibit reversible PC behavior.After the illumination by xenon lamp,the colors of the ceramics change from pale green to gray,and then reversibly recover to their initial state via thermal stimulus(200℃for 10 min).Interestingly,both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process.The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices.