Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics

The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O₃ antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFE_A-AFE_B or ferroelectric FE_L-FE_H transition, which are not detected by the conventional dielectric measurement.     

Properties of PbLa（Zr,Sn, Ti）O3 ceramics near ferroelectric-antiferroelectric phase boundary

Shirane found in the middle of the 20th century that the solid solution PZT had a lot of fine characteristics and carried out detailed researches[1]. The critical phase transition field of antiferroelectric decreased by adding titanate. Titanate expands t…     

PbO对Pb(Zr0.52Ti0.48)O3压电陶瓷性能的影响

采用固相反应的方法制备了Pb(Zr0.52Ti0.48)O3(PZT)压电陶瓷,研究了过量PbO对Pb(Zr0.52Ti0.48)O3压电陶瓷性能的影响。通过XRD和SEM研究了PbO过量对Pb(Zr0.52Ti0.48)O3压电陶瓷的晶相结构及显微形貌的影响,研究结果表明PbO过量不会影响Pb(Zr0.52Ti0.48)O3材料的相结构(均为钙钛矿结构),但是PbO过量太多,会出现过烧现象及气孔等,PbO过量为5%mol时结晶最好。测量了样品的密度、电阻率、压电系数以及介电性能,对这些测量结果的研究表明采用850℃预烧、1 250℃终烧的烧结工艺,PbO过量为5%mol的Pb(Zr0.52Ti0.48)O3压电陶瓷致密性好,密度最大,且具有良好的介电与压电性能,其压电系数最大为322 pC/N。     

应力对外延Pb(Zr,Ti)O3薄膜铁电性能的影响

应用朗道热力学理论研究了应力对Pb(Zr,Ti)O3陶瓷薄膜的相结构及介电特性的影响。结果表明:应力诱导结构相变,居里温度随应变(压应变或张应变)作用的增大而升高,有利于铁电相的稳定;讨论了极化-电场的滞回现象,剩余极化达50μC/cm2,计算结果与实验结果符合较好。     

PbO对Pb(Zr0.52Ti0.48)O3陶瓷相成分的影响

采用固相反应法制备了一系列Pb(Zr0.52Ti0.48)O3压电陶瓷,研究了过量PbO对PZT陶瓷相成分的影响.用X射线衍射对陶瓷的相结构进行了分析,采用场发射扫描电镜对断面形貌进行表征,并用能谱仪对微观区域的陶瓷成分进行测试.实验结果表明:当PbO缺乏时,陶瓷上表面易出现由PbZrO3分解产生的ZrO2,下表面易出现PbTi3O7和焦绿石相.当PbO过量时,陶瓷微观区域的成分会发生波动,成分的一致性也将受到破坏.此外,过量PbO还将使PZT相结构发生向富钛方向的移动.采用先进的陶瓷制备工艺有助于克服成分波动和相结构变化现象.     

胶束法制备Pb（Zr0.53Ti0.47）O3超细粉

用胶束法制得了Ｐｂ（Ｚｒ０．５３Ｔｉ０．４７）Ｏ３超细粉末，避免了在热处理过程中的硬团聚现象，用Ｘ－射线衍射分析，透射电镜等测试手段对粉料进行了表征。制得的超细粉属四方晶系，单颗粒的形貌近似球形，单颗粒平均粒径小于０．１μｍ。     

脉冲激光沉积法制备的Pb(Zr0.4Ti0.6)O3铁电薄膜漏电机理

利用准分子脉冲激光器在Pt/Ti/SiO2/Si(111)衬底上制备了Pb(Zr0.4Ti0.6)O3(PZT)铁电薄膜.利用掩膜技术,采用磁控溅射法在PZT薄膜上生长Pt上电极,构架了Pt/PZT/Pt铁电电容器异质结.采用X射线衍射和电容耦合测试技术分别表征了PZT铁电薄膜的微结构和电学性能.研究发现:在5 V的测试电压下,在560℃较低的沉积温度下生长的PZT薄膜电容器的剩余极化强度为187 C/m2、矫顽电压为2.0 V、漏电流密度为2.5×10-5A/cm2.应用数学拟合的方法研究了Pt/PZT/Pt的漏电机理,发现当电压小于1.22 V时,Pt/PZT/Pt电容器对应欧姆导电机理;当电压大于2.30 V时,对应非线性的界面肖特基传导(Schottky emission)机理.     

Effects of temperature on hydrostatic pressure-induced FE-AFE phase transition in PbLa(Zr, Sn, Ti)O3 ceramics

Hydrostatic pressure-induced ferroelectricantiferroelectric (FE-AFE) phase transition and the pressure dependence of dielectric properties in La-doped Pb(Zr,Sn, Ti)O₃ ceramics were researched; the effects of temperature on hydrostatic pressure-induced FE-AFE phase transition and dielectric properties of the samples were studied. It was found that the temperature made the FE-AFE phase transition pressure decrease, and there existed the behavior of dielectric frequency dispersion and phase transition diffusion in the dielectric-pressure spectrum. These phenomena were very useful to enrich and develop the knowledge on the diffused phase transition behavior of polycomponent relaxor ferroelectric.     

等静压和温度作用下Pb(Zr,Sn,Ti)O3陶瓷的介电性能研究

对反铁电-铁电相界附近的Nb掺杂Pb(Zr,Sn,Ti)O3陶瓷，采用2GPa等静压装置测试了其在不同等静压力下的介电温度性能，分析了各种介电异常，发现了精细的相变特性，指出随着温度升高，在较低的等静压范围内发生反铁电-铁电-顺电相变，而在较高的等静压范围内发生反铁电-顺电相变，其中，铁电相分为微弱频率弥散的弛豫型铁电相和正常铁电相两个不同的介电性能区域，最后，得到了该组分材料的温度-等静压相图。     

准同型相界附近0.02Pb(Zn_(1/3)Nb_(2/3))O_3-0.50Pb(Ni_(1/3)Nb_(2/3))O_3-0.48Pb(Zr_xTi_(1-x))O_3陶瓷压电性能研究

采用传统固相反应法制备四元系0.02Pb(Zn1/3Nb2/3)O3-0.50Pb(Ni1/3Nb2/3)O3-0.48Pb(ZrxTi1-x)O3(0.29≤x≤0.34)陶瓷.观察样品的晶相结构和显微结构,测试压电性能和介电性能.随着Zr/Ti比的增大,晶相从四方相向三方相转变.发现准同型相界位置在x=0.32附近.1 240℃烧结的0.02PZN-0.50PNN-0.48PZ32T陶瓷展现了良好的压电性能,压电常数d33为715 p C/N,机电耦合系数kp为0.541,剩余极化强度Pr为25.5μC/cm2,矫顽场强Ec为5.6 k V/cm.新的压电材料适合高性能压电器件应用,且简单的制备方法给生产带来极大便利.     

外延Pb(Zr0.2Ti0.8)O3薄膜中畴生长与所加脉冲的关系

采用柱状畴的理论模型,研究了用原子力显微镜的探针在外延Pb(Zr_0.2Ti_0.8)O₃薄膜中形成的纳米畴的生长与所加脉冲的关系。指出在PZT薄膜中畴的半径随所加脉冲的持续时间的增加以对数方式增大,随脉冲电压的增加而线性增大。理论计算与试验结果相吻合。     

Nd掺杂Bi4Ti3O12陶瓷样品的铁电、介电性能

层状钙钛矿铁电体材料B i4-xN dxT i3O12(x=0.0~0.9)陶瓷样品适量N d掺杂可提高B i4T i3O12(B IT)的铁电性能.当掺杂量为0.6时,样品的剩余极化达到最大值.样品的相变温度(tc)随掺杂量的增加而降低,当掺杂量大于0.6时,tc下降速率增大.随着N d含量的增加(x>0.6),样品的弛豫程度明显提高.N d掺杂降低了样品的氧空位浓度,提高了B IT样品的铁电性能.     

0.94(Bi0.5Na0.5)TiO3-0.06Ba(Zr0.25Ti0.75)O3陶瓷的制备、表征与热释电性能

以BaCO3、Na2CO3、TiO2、ZrO2和Bi2O3为原料,通过固相反应法合成了铁电粉末材料0.96(Bi0.5Na0.5)TiO3-0.04Ba(Zr,Ti)O3(BNT-BZT),采用常压烧结法制备了BNT-BZT陶瓷片.考察压力和烧结温度对陶瓷致密性的影响,并对BNT-BZT粉末和陶瓷片的结构、形貌和成分进...     

Shock wave compression of poled Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 ceramics: Depoling currents in axial and normal modes

We used a 100-mm diameter gas gun to investigate the output currents due to the sudden depolarization of poled Pb 0.99 [(Zr 0.90 Sn 0.10) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics under shock wave compression.We conducted shock wave experiments for the normal/axial mode with the polarization vector perpendicular/antiparallel to the shock vector.The shock pressure was in the range of 0.23 to 4.50 GPa.We measured the depoling currents under short-circuit,high-impedance,and breakdown conditions.Under the short-circuit condition,the dependence of the released charge on the shock pressure demonstrates the evolution of the ferroelectric-to-antiferroelectric phase transition.The onset pressure of the phase transition is between 0.23 and 0.61 GPa,and phase transition occurs completely above 1.22 GPa.The increasing load resistance decreases the released charge and increases the released energy.The results indicate that Pb[(ZrSn)Ti]NbOceramic is a good candidate for a pulsed power generator.     

Elastic anomalies near phase transitions of lead-free （Na,Bi）TiO3 and （Ba,Zr）TiO3 ferroelectric ceramics

We have investigated the temperature dependence of elastic modulus for various ferroelectric ceramics in the temperature range of 20–90°C.The Na0.5Bi0.5TiO3(NBT)ceramics has a phase transition at 200°C,thus exhibits minimal change in elastic modulus up to 90°C,while the elastic modulus of the BaZr0.07Ti0.93O3(BZT-7)shows 12.5%change at the phase transition temperature of70°C and that of the BaZr0.15Ti0.85O3(BZT-15)ceramics shows 34.6%change at the phase transition temperature of60°C.The variations of elastic modulus will affect the temperature stability of devices made by these lead-free ferroelectric ceramics.     

CaCu3Ti4O12陶瓷显微结构及介电性能

采用固相法制备CaCu3Ti4O12陶瓷,并对其烧结温度、晶相结构、致密化过程、显微结构及介电性能与频率的关系进行了研究。研究发现,不同烧结温度下,1000℃制备的CaCu3Ti4O12陶瓷为立方钙钛矿结构且结晶完好,晶格常数为7.394?。CaCu3Ti4O12陶瓷具有良好的显微形貌,结构致密,平均晶粒尺寸在3-5μm。CaCu3Ti4O12陶瓷在10kHz处的介电常量高达7200,介电损耗约为0.06。     

PZT 基铁电陶瓷材料 F-P 相变及其热物理性质

用激光闪光法研究了ＰＺＴ为基铁电陶瓷材料［Ｐｂ（Ｓｂ，Ｎｂ，Ｚｒ，Ｔｉ）Ｏ３］的ＦＰ相变及其热物理性质。实验发现，铁电相到顺电相的变化发生时，热扩散率和导热系数随温度发生异常变化。根据其热物性曲线出现的突变点所确定的相变温度与用电学法测定的居里温度ＴＣ吻合良好。据此，闪光法可以作为研究铁电材料相变的一个新的手段和判据。     

The abnormal sensitivity and its mechanism of （Ba, Pb）TiO3 semiconductor ceramics

The resistance-temperature properties of porous (Ba, Pb)TiO3 semiconductor ceramic were systematically studied. It was found that the resistance of (Ba, Pb)TiO3 ceramic having been placed in the air for a long time was abnormally increased with the increase of the temperature from the room temperature to 70℃ prior to the Curie point. Further research showed that this abnormal resistance-temperature property was linked to its humidity sensitivity. When the relative humidity changed from 11% to 93%, the resistance of (Ba, Pb)TiO3 ceramic decreased three orders of magnitude. Furthermore, the humidity-resistance was approximately linear in single logarithm coordinate. According to the surface adsorption, grain-boundary potential barrier and ferroelectric-paraelectric phase transformation, the specific sensitive mechanism of (Ba, Pb)TiO3 ceramic was analyzed qualitatively.     

LaNiO3衬底上SrBi4Ti4O15薄膜的sol-gel方法制备

采用溶胶-凝胶法在S i(111)衬底上制备了LaN iO3薄膜,采用相同方法在LaN iO3/S i(111)上制备了SrB i4Ti4O15(SBT)薄膜,对SrB i4Ti4O15(SBT)薄膜的结晶性,厚度和电性能进行了研究.     

Research on effects of hydrostatic pressure on the dielectric property of Pb(Zn 1/3Nb2/3) O3-Ba Ti O3PbTiO3 relaxor ferroelectric ceramics

The dielectric properties of Pb(Zn1/3Nb2/3)O3BaTiO3-PbTiO3 relaxor ferroelectric ceramics near the rhombohedral and tetragonal phase boundary were investigated under hydrostatic pressure. It was found that hydrostatic pressure made their phase transition temperature Tc and the peak temperature Tm decreased, and the frequency dispersion and relaxor behavior enhanced. In these disorder systems of composite pervoskite structures, there appeared polar clusters or nanodomains. The unique physical characteristics, which made the relaxor behavior enhanced, is that the correlation length among these nanodo- mains decreases greatly with the pressure increasing.