La调节Pb(Zr,Sn,Ti)O_3反铁电陶瓷的相变与电学性质

利用X射线衍射、弱场介电温度谱、强场极化强度研究了不同La含量(Pb1-xLa2x3)(Zr06Sn03Ti01)O3(000≤x≤012)(PLZSnT)陶瓷的相变与电学特性.实验发现,随La含量增大,室温下材料由铁电三方相(x=000)转变为反铁电四方相(003≤x≤009)和立方相(x=012).介电测试表明,La含量增大,反铁电→顺电相变温度降低,峰值介电常量减小.在x=006的PLZSnT三元相图中,反铁电四方相区扩大到Ti含量约为18at%,该系统反铁电陶瓷具有“窄、斜”型双电滞回线和“三电滞回线”;在高Zr、高Sn区,反铁电→顺电相变呈现弥散相变和介电频率色散特征,即反铁电极化弛豫现象.从ABO3钙钛矿结构的容忍因子(t)和反铁电相的结构特征出发,讨论了La对Pb(Zr,Sn,Ti)O3相变与电学性质的影响机理 关键词： 场诱相变 弛豫型反铁电体 介电性能 La调节Pb(Zr Sn Ti)O3     

Nanosecond domain wall dynamics in ferroelectric Pb(Zr, Ti)O(3) thin films

Domain wall motion during polarization switching in ferroelectric thin films is fundamentally important and poses challenges for both experiments and modeling. We have visualized the switching of a Pb(Zr, Ti)O(3) capacitor using time-resolved x-ray microdiffraction. The structural signatures of switching include a reversal in the sign of the piezoelectric coefficient and a change in the intensity of x-ray reflections. The propagation of polarization domain walls is highly reproducible from cycle to cycle of the electric field. Domain wall velocities of 40 m s(-1) are consistent with the results of other methods, but are far less than saturation values expected at high electric fields.     

Electromechanical-induced antiferroelectricben ferroelectric phase transition in PbLa(Zr,Sn,Ti)O3 ceramic

Antiferroelectric—ferroelectric (AFE—FE) phase transition in ceramic Pb_0.97La_0.02(Zr_0.75Sn_0.136Ti_0.114)O₃ (PLZST) was studied by dielectric spectroscopy as functions of frequency (10²—10⁵ Hz) and pressure (0—500 MPa) under a DC electric field. The hydrostatic pressure-dependent remnant polarization and dielectric constant were measured. The results show that remnant polarization of the metastable rhombohedral ferroelectric PLZST poled ceramic decreases sharply and depoles completely at phase transition under hydrostatic pressure. The dielectric constant undergoes an abrupt jump twice during a load and unload cycle under an electric field. The two abrupt jumps correspond to two phase transitions, FE—AFE and AFE—FE.     

Pb(Zr1-xTix)O3中组分调制诱导的不寻常的铁电相

Pb(Zr1-xTix)O3(PZT)是一种重要的钙钛矿结构铁电固溶体，在其准同型相界处发现单斜相引起研究的热潮，文章报道了作者最近对沿着[100]赝立方方向组分调制的PZT体系的铁电性质的研究结果，发现组分调制导致极化偏离调制方向，在准同型相界附近诱导出新型的铁电三斜相和C型单斜相，以及极高的机电特性，证明偶极相互作用是导致以上行为的主要微观机制。     

Shock-wave- and hydrostatic-pressure-induced depolarization of Pb(Zr,Sn,Ti)O3 for pulse power applications

Research on quasi-static pressure-induced depolarization illustrates that Pb(Zr,Sn,Ti)O₃ ceramic may be useful in the technology of pulse power. However, lack of knowledge on the shock-induced depolarization hinders this application. To fill this gap, we investigated the shock-wave- and hydrostatic-pressure-induced depolarization of Pb_0.99Nb_0.02[(Zr_0.90Sn_0.10)_0.96Ti_0.04]_0.98O₃ ceramic. In the hydrostatic experiment, complete and sudden depolarization took place at 140 MPa. Shock wave experiments in the normal and axial modes were conducted in the pressure range from 0.81 to 4.50 GPa. At 2.50 GPa, the phase transition occurred completely and the short-circuit current reached 32 A in the normal mode. We obtained 31.0 kV voltage, 0.96 MW and 0.92 J cm^?3 high-voltage pulse with 1000 Ω load. In the axial mode, the shape of the current pulse and its time integral were found to be strongly shock pressure dependent. Our work lays the foundation for the application of Pb(Zr,Sn,Ti)O₃ in the single-use power supply.     

Pb(Zr0.3Ti0.7)O3铁电薄膜激光感生电压效应

采用脉冲激光沉积(PLD)技术在LaSrAlTaO₃(LSATO),LaAlO₃(LAO)和SrTiO₃(STO)的单晶倾斜衬底上成功制备了Pb(Zr_0.3Ti_0.7)O₃(PZT)薄膜,在三种倾斜衬底上生长的PZT薄膜中都首次发现了LIV效应.对PZT/LSATO薄膜在a,c轴两种不同取向择优生长下的LIV效应做了研究,发现在薄膜c轴取向择优生长 关键词： 激光感生电压效应 铁电薄膜 薄膜生长取向 原子层热电堆     

Effect of electric-field-assisted thermal treatment on the strain and ferroelectric properties of (100)-oriented ferroelectric Pb(Zr0.52Ti0.48)O3 thin films

Ferroelectric Pb(Zr_0.52Ti_0.48)O₃ thin films were deposited on the Pt/Ti/SiO₂/Si substrate by a sol-gel method. As a direct electric field was applied on the films during thermal treatment, strain behavior and ferroelectric properties have been investigated. X-ray diffraction patterns show that great tensile strain exists nearby the interface of the 250 nm thin film while thermal treatment assisted with direct electric field can obviously relax it. The analysis of hysteresis loops indicates that the remnant polarization increases with the thermal treatment time. These results suggest that electric-field-assisted thermal treatment is an effective way to reduce films' tensile strain through the local plastic deformation in Pt layer and enhance the remnant polarization.     

Domain,dielectric and optical studies in antiferroelectric (Pb,La) (Zr,Sn, Ti)O3 single crystals

Antiferroelectric (Pb, La) (Zr, Sn, Ti)O₃ (PLZST) single crystals have been successfully grown by flux method using PbO–PbF₂–B₂O₃ as the flux. The obtained crystals are pale yellow in color and translucent. Domain structures, dielectric constants and optical transmission measurements have been performed on the 〈001〉-oriented PLZST single crystals. Two types of domains, namely, 90° and 180° domains, are observed. The extinction of 90° domains at P/A: 0° reveals a tetragonal structure in the crystal. The sequence of phase transitions from antiferroelectric to ferroelectric and then paraelectric has been established with increasing temperature. According to the modified Curie–Weiss relationship, the PLZST crystal is in an intermediate state between normal and relaxor antiferroelectrics. The broad optical transparent region (from 0.4 to 7.0 μm) and high optical transmittance (up to 65%) indicate that PLZST crystals are promising for optical uses.     

直流偏压对压力诱导反铁电陶瓷去极化性能的影响

采用掺铌的锆钛锡酸铅（PNZST）反铁电陶瓷作为研究对象,研究了不同的直流电场作用下,等静压力诱导极化态反铁电陶瓷发生去极化过程（同时发生铁电/反铁电相变）的规律.当极化态样品两端电场强度为6 kV/cm时,去极化压力为128.8 MPa;当极化态样品两端电场强度为-6 kV/cm时,去极化压力为74.2 MPa.在与极化电场方向相反的外加电场作用下极化态样品具有较小的去极化压力.讨论了外加直流电场影响极化态反铁电陶瓷去极化压力的内在机理.得到了不同外置电场下的去极化压力,并绘制了该材料的外加直流电场（< 关键词： 去极化 反铁电体 相变     

Evolution of electric response of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 and Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 ferroelectric ceramics under shock wave compression

The objective of this work is to investigate the dependence of the electric behavior on shock pressure in Pb_0.99(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ (PZT 95/5-2Nb) and Pb_0.99[(Zr_0.90Sn_0.10)_0.96Ti_0.04]_0.98Nb_0.02O₃ (PZST) ferroelectric ceramics under shock wave compression. PZT 95/5-2Nb and PZST ceramics were subjected to high dynamic pressure generated by plate impacts. The output currents were measured under the short-circuit condition in the pressure range from 0.23 to 4.50 GPa. The evolution of the electric response exhibits three distinct regions: (1) Below the critical phase transition pressure (σ_C), alternate negative and positive piezoelectric currents are observed and the corresponding piezoelectric constant is e ₃₁. (2) Above σ_C and below the complete phase transition pressure (σ_H), released charge increases with increasing shock pressure, illustrating the transition of ferroelectric to antiferroelectric phase. (3) Above σ_H, the output current is insensitive to the shock pressure. A similar evolutionary process is also observed in hydrostatic and uniaxial stress experiments.     

Structural refinement,optical and ferroelectric properties of microcrystalline Ba(Zr0.05Ti0.95)O3 perovskite

For this study, a microcrystalline Ba(Zr_0.05Ti_0.95)O₃ (BZT) powder was prepared by a high energy ball milling method followed by calcination at 1100 °C for 4 h. The calcined powder was structurally characterized by X-ray diffraction and Rietveld refinement data, which showed that this material has a perovskite-type tetragonal structure with a space group of (P4mmm). The micro-Raman spectrum revealed local lattice distortions due to distorted octahedral [TiO₆] clusters. The temperature and frequency-dependent dielectric study of the BZT ceramic showed normal phase transition behavior. The ferroelectric property was studied by a P–E hysteresis loop. Optical band gap was investigated by ultraviolet–visible (UV–vis) absorption spectroscopy at room temperature. The UV–vis spectrum indicated that the BZT powder has an optical band gap of 3.15 eV.     

Domain wall creep in epitaxial ferroelectric Pb(Zr(0.2)Ti(0.08)O(3) thin films

Ferroelectric switching and nanoscale domain dynamics were investigated using atomic force microscopy on monocrystalline Pb(Zr(0.2)Ti(0.8))O(3) thin films. Measurements of domain size versus writing time reveal a two-step domain growth mechanism, in which initial nucleation is followed by radial domain wall motion perpendicular to the polarization direction. The electric field dependence of the domain wall velocity demonstrates that domain wall motion in ferroelectric thin films is a creep process, with the critical exponent mu close to 1. The dimensionality of the films suggests that disorder is at the origin of the observed creep behavior.     

不同衬底上Pb(Zr0.52Ti0.48)O3择优取向铁电薄膜的制备和研究

通过MOD法在Si(100)和Pt(111)/Ti/SiO2/Si基片上制备出LaNiO3 (LNO)薄膜.再通过修正的Sol-gel法,在Pt(111)/Ti/SiO2/Si,LNO/Si(100)和LNO/Pt/Ti/SiO2/Si三种衬底上制备出具有择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜.经XRD分析表明,LNO薄膜具有(100)择优取向的类钙钛矿结构;PZT薄膜均具有钙钛矿结构,且在Pt(111)/Ti/SiO2/Si衬底上的薄膜以(110)择优取向,在LNO/Pt/Ti/SiO2/Si和LNO/Si(100)衬底上的薄膜以(100)择优取向.经场发射SEM分析和介电、铁电性能测试表明,在LNO/Si和LNO/Pt/Ti/SiO2/Si衬底上的PZT薄膜的平均粒径、介电常数以及剩余极化强度均比以Pt/Ti/SiO2/Si为衬底的薄膜大.     

Experimental study of the built-in field in intergrain channels of thin ferroelectric Pb(Zr,Ti)O3 films

The experimentally measured dependence of the photo-emf on the remanent polarization in thin-film M/Pb(Zr,Ti)O₃(PZT)/M capacitors correlates well with the model developed by us for the intergrain photovoltaic effect for films with columnar structure of PZT grains and heterophase intergrain boundaries. In this case, the photo-emf is determined by the depolarization field generated by the uncompensated polarization charge at PZT grain boundaries. It is shown that the magnitude and orientation of the built-in field in an intergrain channel of such PZT films can be derived from measurements of the photo-emf at zero polarization with a sensitivity on the order of a few millivolts.     

Pb(Zr,Sn,Ti)O3反铁电陶瓷的低温相变扩散与极化弛豫

用弱场介电温谱、热释电流谱、强场电滞回线和变温X射线衍射谱研究了微量La掺杂Pb(Zr ,Sn ,Ti)O3(PZST)反铁电 (AFEt)陶瓷在 - 10 0— 180℃温区内的结构与电学特性 .弱场介电温谱显示 ,AFEt陶瓷在低温段(- 10 0— 5 0℃ )呈现介电频率弥散 (0 1— 10 0kHz)和扩散型相变的特征 ,而变温X射线衍射谱却表明材料在这一温区内保持四方相结构 ;低温下经强场作用后 ,AFEt被诱导为亚稳三方铁电态 ,介电频率弥散消失 .基于多元复杂化合物的组分起伏理论 ,讨论了PZSTAFEt陶瓷的相变扩散与极化弛豫新现象 .