High piezoelectricity after field cooling AC poling in temperature stable ternary single crystals manufactured by continuous-feeding Bridgman method

After field cooling(FC)alternating current poling(ACP),we investigated the dielectric and piezoelectric properties of[001]_(pc)-oriented 0.24Pb(In_(1/2)Nb_(1/2))O_(3)(PIN)-0.46Pb(Mg_(1/3)Nb_(2/3))O_(3)(PMN)-0.30PbTiO3(PT)(PIMN-0.30PT)single crystals(SCs),which were manufactured by continuous-feeding Bridgman(CF BM)within morphotropic phase boundary(MPB)region.By ACP with 4 kVrms/cm from 100 to 70℃,the PIMN-0.30PT SC attained high dielectric permittivity of 8330,piezoelectric coefficient(d_(33))of 2750 pC/N,bar mode electromechanical coupling factorκ_(33)of 0.96 with higher phase change temperature(T_(pc))of 103℃,and high Curie temperature(7c)of 180℃.These values are the highest ever reported as PIMN-xPT SC system with Tpc>100℃.The enhancement of these properties is attributed to the induced low symmetry multi-phase supported by phase analysis.This work indicates that FC ACP is a smart and promising method to enhance piezoelectric properties of relaxor-PT ferroelectric SCs including PIMN-xPT,and provides a route to a wide range of piezoelectric device applications.

Ceramic synthesis of 0.08BiGaO_3–0.90BaTiO_3–0.02LiNbO_3 under high pressure and high temperature

In this paper, the preparation of 0.08BiGaO3–0.90BaTiO3–0.02LiNbO3 is investigated at pressure 3.8 GPa and temperature 1100–1200？C. Experimental results indicate that not only is the sintered rate more effective, but also the sintered temperature is lower under high pressure and high temperature than those of under normal pressure. It is thought that the adscititious pressure plays the key role in this process, which is discussed in detail. The composition and the structure of the as-prepared samples are recorded by XRD patterns. The result shows that the phases of Ba TiO3, BaBiO（2.77）, and Ba2Bi4Ti5O（18） with piezoelectric ceramic performance generate in the sintered samples. Furthermore, the surface morphology characteristics of the typical samples are also investigated using a scanning electron microscope. It indicates that the grain size and surface structure of the samples are closely related to the sintering temperature and sintering time. It is hoped that this study can provide a new train of thought for the preparation of lead-free piezoelectric ceramics with excellent performance.

Review on high temperature piezoelectric ceramics and actuators based on BiScO_(3)–PbTiO_(3) solid solutions

In recent years,industries in the fields of petrochemical,automotive,and aerospace have expressed their interest in utilizing piezoelectric actuators for high-temperature(HT)operations at the temperature above 150℃.HT piezoelectric ceramics(1x)BiScO_(3-x)PbTiO_(3)(BS-PT)are considered as one of the most competitive piezoelectric actuation materials used in the harsh environment because of its high Curie temperature(T_(C)=450℃)as well as high piezoelectric coefficient(d_(33)=460 pC/N)in the MPB composition.This paper summarized the recent progress in HT piezoelectric ceramics and actuators based on BS-PT solid solutions.The properties of BS-PT piezoelectric ceramics and actuators,including driving mechanisms,actuation performances and their applications in HT environment were also discussed.

HIGH PIEZOELECTRIC PERFORMANCE AND RELEVANT PHYSICAL MECHANISM OF CuO-MODIFIED Ba(Ti_(0.96)Sn_(0.04))O_(3)CERAMICS

Ba(Ti_(0.96)Sn_(0.04))O_(3)and CuO-modified Ba(Ti_(0.96)Sn_(0.04))O_(3)ceramics were prepared by the solid state reaction technique.Their piezoelectric properties were investigated and compared with those of the recently obtained high-d_(33)BaTiO_(3)ceramic.It has been found that simply substituting Ti4t with Sn4t worsens severely the piezoelectric properties whereas a combined usage of CuO additive greatly improves the overall piezoelectric performance.CuO-modified BaeTi_(0.96)Sn_(0.04)TO_(3)ceramic shows excellent piezoelectric properties of d_(33)=390 pC=N;kp=0.49 and k33=0.67 at room temperature.Furthermore,it possesses weak temperature dependences of electromechanical coe±cients between
20 and 55 and a good thermal aging stability down to a low experimental temperature limit of
50℃and up to 90.Detailed analysis suggests that its high piezoelectric performance should be largely ascribed to the ideal microstructure of high relative density and small grains and the corresponding domain configurations.

Homogenous Sn-doped K(Ta,Nb)O_(3) single crystals and its high piezoelectric response

Perovskite K(Ta,Nb)O_(3)(KTN)single crystal has drawn great interests for its outstanding electro-optic performance and excellent piezoelectric response.However,growth of compositionally uniform KTN single crystals has always been a great challenge for the great segregation difference between Nb and Ta.In this work,we propose a thermal field optimization strategy to resolve this challenge.Homogenous Sn doped KTN(Sn:KTN)single crystal with significantly reduced composition gradient(0.003 mol/mm,1/4 e1/8 of other KTN system),minimal TC variation(13℃)and excellent piezoelectric and dielectric response(d_(33)=373 pC/N andε^(T)_(33)=5206)has been successfully achieved.We found that the functional properties of Sn:KTN were greatly affected by the near-room temperature tetragonal-cubic phase transition.From the intrinsic aspect,longitudinal lattice deformation becomes much easier,resulting in maximum piezoelectric(d^(*)_(33)),dielectric(ε^(T*)_(33)),elastic(s^(E*)_(33))and electromechanical coupling(k^(*)_(33))coefficients along polar direction[001]_(C).From the extrinsic aspect,both domain wall density and domain wall mobility are greatly improved for the reduced lattice distortion,which also contribute a lot to the functional properties.This work provides a simple and practical route for designing and growing high quality crystals,and more importantly,reveals the fundamental mechanism of the phase transitions/boundaries on the functional properties.

High piezoelectric properties and good temperature stabilities of CuO-modified Ba(Ti_(0.96)Sn_(x)Zr_(0.04-x))O_(3) ceramics

In order to obtain both high piezoelectric property and good temperature stability in BaTiO_(3)-based ceramics in the common usage temperature range,Sn4þand Zr4þare co-doped into BaTiO3 ceramics according to the formula of Ba(Ti_(0.96)Sn_(x)Zr_(0.04-x))O_(3)(BTSZ)(x=0.01-0.4)with 1 mol%CuO being added as sintering-aid in this study.The CuO-modified BTSZ ceramics show both high piezoelectric properties and good temperature stability.Particularly,the CuO-modified Ba(Ti_(0.96)Sn_(x)Zr_(0.04-x))O_(3)ceramic displays the high piezoelectric properties of d_(33)=350 pC/N,k_(p)=49.5%at room-temperature and a weak temperature dependence of kp in the temperature range of
15C and 60C.Moreover,the CuO-modified Ba(Ti_(0.96)Sn_(x)Zr_(0.04-x))O_(3)ceramic shows stable thermal aging behavior with the d33 being almost unchanged until the aging temperature of 100C,which is even higher than its Curie temperature.The high piezoelectric properties of CuO-modified Ba(Ti_(0.96)Sn_(x)Zr_(0.04-x))O_(3)ceramic were ascribed to the dense microstructure with small and uniform grain size distribution.The stable thermal aging behavior can be explained by the aging effect based on the defect dipolar model.

Effect of Zr^(4+)on piezoelectric,dielectric and ferroelectric properties of barium calcium titanate lead-free ceramics

Ba_(0.85)Ca_(0.15)(Ti1−xZrx)O_(3)(BCTZ)ceramics with x=0.05,0.10,_(0.15),0.20,0.25,0.30 were prepared by the solid-state reaction method.Calcination of the powders was carried out at 1100°C for 4 h and the green pellets were sintered at 1400°C for 2 h.X-ray diffraction patterns of the sintered pellets showed tetragonal splitting up to x=0.10 while the mixture of the rhombohedral/cubic phase appeared at higher ZrO_(2)concentrations.Maximum piezoelectric charge constant d33=510 pC/N and strain(S=0.103%)were measured for BCT doped by 0.10 mol ZrO_(2).Dielectric constant,remnant polarization and saturation polarization also found maxima for this composition.The Curie temperature(TC)of the compositions decreased with increase in ZrO_(2)concentration and reached 98°C,87°C and 36°C at x=0.05,0.10,_(0.15)mol,respectively.The remaining compositions have TC below the room temperature;therefore,they can be used for subzero/cryogenic applications.The scanning electron microscopy study revealed an increase in grain size with increase in ZrO_(2)concentration and confirmed the complete solubility of ZrO_(2)in the crystal lattice.Overall,low ZrO_(2)-doped BCT compositions with high d33 could be suitable for low temperature(<80°C)applications.