铁电陶瓷在外电场作用下的畴变行为与其宏观性质直接相关，掌握外场作用下的铁电畴变行为对研究其非线性行为、失效机理、提高可靠性具有重要的理论指导意义。但是迄今而止，仍没有一个能够较为精确模拟材料的非线性行为且被普遍接受的本构方程。本论文将电加载装置与X射线衍射仪联用，通过自行合成特定组成和结构的掺镧锆钛酸铅(PLZT)陶瓷材料，在外加直流电场作用下对PLZT畴变进行了原位XRD观测，得到相关参数值，从而改进了现有的非线性本构方程，探讨了将实验测试结果用于表征四方相PLZT铁电畴变与材料宏观极化强度之间的关系，为进一步理解铁电体的非线性行为奠定基础。 结果表明，通过传统固相法合成的理论化学组成为P...Domain switching of ferroelectric ceramics under an application of electric fields is directly related to their macroscopic properties. It is important to understand the domain switching behavior of ferroelectrics in order to study the nonlinear behavior, failure mechanism and improving reliability. However, the widely accepted constitutive equations used to precisely simulate the nonlinear behavi...学位：工学硕士院系专业：材料学院_固体力学学号：2072010115012

刘莹

Xiamen University Institutional Repository

学校编码：10384                                 分类号       密级         学号：20720101150120                                         UDC                 硕  士  学  位  论  文    掺镧锆钛酸铅铁电陶瓷电致畴变的原位 XRD 分析 In-situ XRD Analysis of Electric Induced Domain Switching in PLZT Ferroelectric Ceramics  刘 莹  指导教师姓名：张 颖 教 授 专  业 名 称：固 体 力 学 论文提交日期：2013 年 5 月 论文答辩时间：2013 年 5 月 学位授予日期：2013 年 6 月    答辩委员会主席：             评    阅    人：             2013 年 5 月 厦门大学博硕士论文摘要库  厦门大学博硕士论文摘要库   In-situ XRD Analysis of Electric Induced Domain Switching in PLZT Ferroelctric Ceramics  A Thesis Submitted to  the Graduates School in Partial Fulfillment of the Requirements  for the Master Degree of Science  By Ying LIU  Supervised by  Ying ZHANG  Department of Materials Science and Engineering College of Materials  Xiamen University  May, 2013 厦门大学博硕士论文摘要库  厦门大学博硕士论文摘要库厦门大学学位论文原创性声明  本人呈交的学位论文是本人在导师指导下,独立完成的研究成果。本人在论文写作中参考其他个人或集体已经发表的研究成果，均在文中以适当方式明确标明，并符合法律规范和《厦门大学研究生学术活动规范（试行）》。 另外，该学位论文为（                            ）课题（组）的研究成果，获得（               ）课题（组）经费或实验室的资助，在（               ）实验室完成。（请在以上括号内填写课题或课题组负责人或实验室名称，未有此项声明内容的，可以不作特别声明。）  声明人（签名）：           年   月   日         厦门大学博硕士论文摘要库                      厦门大学博硕士论文摘要库厦门大学学位论文著作权使用声明  本人同意厦门大学根据《中华人民共和国学位条例暂行实施办法》等规定保留和使用此学位论文，并向主管部门或其指定机构送交学位论文（包括纸质版和电子版），允许学位论文进入厦门大学图书馆及其数据库被查阅、借阅。本人同意厦门大学将学位论文加入全国博士、硕士学位论文共建单位数据库进行检索，将学位论文的标题和摘要汇编出版，采用影印、缩印或者其它方式合理复制学位论文。 本学位论文属于： （     ）1.经厦门大学保密委员会审查核定的保密学位论文，于   年  月  日解密，解密后适用上述授权。 （     ）2.不保密，适用上述授权。 （请在以上相应括号内打“√”或填上相应内容。保密学位论文应是已经厦门大学保密委员会审定过的学位论文，未经厦门大学保密委员会审定的学位论文均为公开学位论文。此声明栏不填写的，默认为公开学位论文，均适用上述授权。）                                声明人（签名）： 年   月    厦门大学博硕士论文摘库                      厦门大学博硕士论文摘要库摘 要 I  摘 要 铁电陶瓷在外电场作用下的畴变行为与其宏观性质直接相关，掌握外场作用下的铁电畴变行为对研究其非线性行为、失效机理、提高可靠性具有重要的理论指导意义。但是迄今而止，仍没有一个能够较为精确模拟材料的非线性行为且被普遍接受的本构方程。本论文将电加载装置与 X 射线衍射仪联用，通过自行合成特定组成和结构的掺镧锆钛酸铅(PLZT)陶瓷材料，在外加直流电场作用下对 PLZT 畴变进行了原位 XRD观测，得到相关参数值，从而改进了现有的非线性本构方程，探讨了将实验测试结果用于表征四方相 PLZT 铁电畴变与材料宏观极化强度之间的关系，为进一步理解铁电体的非线性行为奠定基础。 结果表明，通过传统固相法合成的理论化学组成为 Pb0.93La0.07(Zr0.52,Ti0.48)O3 的陶瓷材料为典型四方相结构，晶胞参数 a=b=4.045Å，c=4.101Å，c/a=1.014，晶粒平均尺寸 12m，致密度和性能良好，室温下矫顽场强度为 850V/mm，介电常数约 3000，居里温度约为 250oC，极化试样的压电系数约 230pC/N。 在外加直流电场作用下对 PLZT 铁电陶瓷的原位 XRD 测试发现，电极及其制备方式、电场加载顺序、材料的退火处理、电畴应力回转影响未极化的 PLZT 铁电陶瓷蝶形曲线的对称性。外加电场强度的大小和方向导致铁电陶瓷材料衍射峰(002)和(200)的相对强度(I(002)/(I(002)+I(200)))发生明显的变化，高达 7%的 a 畴会在电场卸载瞬间发生回转。 通过假设铁电多晶材料的介电系数受电畴翻转的影响和自发极化强度正比于材料表面的c畴数，基于原位XRD衍射峰强I(002)/(I(002)+I(200))随外加电场变化结果，建立了多晶铁电陶瓷材料宏观极化强度随外加电场变化的模型，该模型能够从微观畴变行为的角度描述铁电体在电场循环作用下的非线性行为，从而改进了现有的非线性本构方程。在外电场的作用下，畴变本身比介电响应对四方相PLZT铁电陶瓷极化强度的影响更为显著。  关键词：掺镧锆钛酸铅铁电陶瓷；原位 XRD 测试；本构方程  厦门大学博硕士论文摘要库厦门大学硕士学位论文 II                            厦门大学博硕士论文摘要库Abstract III  Abstract Domain switching of ferroelectric ceramics under an application of electric fields is directly related to their macroscopic properties. It is important to understand the domain switching behavior of ferroelectrics in order to study the nonlinear behavior, failure mechanism and improving reliability. However, the widely accepted constitutive equations used to precisely simulate the nonlinear behavior of materials are not available. This work was carried out to investigate the domain switching of self-made PLZT ferroelectric ceramics with specific composition and structure under the applications of DC electric fields using in-situ XRD measurements by combing a self-designed electric-loading device with the X-ray diffractometer. The existing constitutive equations were modified with the experimentally determined parameters and the relations between the domain switching behavior of tetragonal phase PLZT ceramic and its macroscopic polarization were explored based on the in-situ XRD data obtained with the unpoled PLZT ceramic specimens. This work would provide a fundamental basis to further understand the nonlinear behavior of ferroelectrics. The results showed that the nominal compositions of Pb0.93La0.07(Zr0.52,Ti0.48)O3 ferroelectric ceramics with a typical tetragonal phase were prepared through a conventional solid-state synthesis route. The lattice parameters were a=b=4.045Å and c=4.101Å with c/a=1.014. The average grain size was 12m. The densities and properties of self-made materials were good. The coercive field was 850kV/mm and the dielectric constant was 3000 at room temperature. The Curie temperature was close to 250oC and the piezoelectric constant of the poled ceramics was nearly 230pC/N. The data obtained by in-situ XRD measurements under the applications of different DC electric fields revealed that the symmetries in the butterfly curves of unpoled PLZT ferroelectric ceramics were significantly affected by electrodes and their preparation method, the orders of electric field loading, the annealing treatment of materials, the stress induced domain stitching. The magnetite and direction of the applied electric field changed 厦门大学博硕士论文摘要库厦门大学硕士学位论文 IV  the relative intensities of (002) and (200) diffraction peaks (I(002)/(I(002)+I(200))) observed from the PLZT ceramics. The amounts of a domain switching were as high as 7% occurred right after the moment by unloading electric field. With both hypotheses that the dielectric constant of the polycrystalline ferroelectrics is affected by domain switching and the spontaneous polarization is proportional to the quantity of c domain on the specimen surface, a model that represented the behavior of the microscopic polarization deduced from variations in the values of I(002)/(I(002)+I(200)) determined by in-situ XRD measurements was developed. The simulation results showed that this model could describe the nonlinear behavior associated with domain switching of ferroelectrics under the cyclic electric fields. Accordingly, the currently existing constitutive equations were modified. It was found that under the applications of cyclic electric fields, domain switching itself has more significant impact than dielectric response on polarization of tetragonal PLZT ferroelectric ceramics.  Key Words: PLZT Ferroelectric Ceramics; In-situ XRD measurement; Constitutive Equations         厦门大学博硕士论文摘要库目 录 V  目 录 摘 要 ..................................................................................................................I Abstract ......................................................................................................... III 第一章 绪论 ..................................................................................................... 1 1.1 铁电陶瓷概述 ........................................................................................................ 1 1.1.1 基本性质 ..................................................................................................... 1 1.1.2 合成方法 ..................................................................................................... 6 1.1.3 掺杂改性 ..................................................................................................... 7 1.2 铁电陶瓷的畴变观测技术 .................................................................................... 9 1.2.1 扫描电子显微镜 ......................................................................................... 9 1.2.2 透射电子显微镜 ....................................................................................... 10 1.2.3 液晶显示 ................................................................................................... 11 1.2.4 近场显微术 ............................................................................................... 12 1.2.5 拉曼光谱 ................................................................................................... 13 1.2.6 X 射线衍射 ................................................................................................ 13 1.3 铁电材料本构方程研究进展 .............................................................................. 15 1.3.1 研究现状 ................................................................................................... 16 1.3.2 畴变对本构方程的影响 ........................................................................... 21 1.3.3 存在问题 ................................................................................................... 25 1.4 本论文的研究目标、内容及创新点 .................................................................. 26 第二章 实验的试样、设备和方法 .............................................................. 29 2.1 药品、设备及方法 .............................................................................................. 29 2.1.1 药品与设备 ............................................................................................... 29 2.1.2 合成方法 ................................................................................................... 30 2.2 表征仪器及方法 .................................................................................................. 31 2.2.1 密度测试 ................................................................................................... 31 2.2.2 扫描电子显微镜 ....................................................................................... 31 2.2.3 X 射线衍射仪 ............................................................................................ 31 厦门大学博硕士论文摘要库厦门大学硕士学位论文 VI  2.2.4 铁电性能测试 ........................................................................................... 32 2.2.5 介电温谱/频谱测试仪 .............................................................................. 32 2.2.6 压电性能测试 ........................................................................................... 32 2.3 电场加载下原位 XRD 测试 ............................................................................... 33 2.3.1 试样准备 ................................................................................................... 33 2.3.2 测试方法 ................................................................................................... 33 第三章 结果与讨论 ....................................................................................... 35 3.1 PLZT 的合成工艺探索........................................................................................ 35 3.1.1 烧结致密度 ............................................................................................... 35 3.1.2 晶粒尺寸 ................................................................................................... 38 3.1.3 晶相结构 ................................................................................................... 40 3.1.4 压片模具 ................................................................................................... 41 3.1.5 合成工艺 ................................................................................................... 42 3.1.6 本节小结 ................................................................................................... 43 3.2 PLZT 的表征 ........................................................................................................ 43 3.2.1 基础信息 ................................................................................................... 43 3.2.1.1 结构分析 ........................................................................................ 43 3.2.1.2 形貌分析 ........................................................................................ 44 3.2.1.3 成分分析 ........................................................................................ 45 3.2.1.4 烧结致密度分析 ............................................................................ 46 3.2.2 电学性能 ................................................................................................... 46 3.2.2.1 铁电性能分析 ................................................................................ 46 3.2.2.2 介电性能分析 ................................................................................ 47 3.2.2.3 压电性能分析 ................................................................................ 48 3.3 I-E 蝶形曲线的影响因素 .................................................................................... 49 3.3.1 电极及其制备方式 ................................................................................... 50 3.3.2 电场加载顺序 ........................................................................................... 55 3.3.3 试样退火处理 ........................................................................................... 57 3.3.4 电畴应力回转 ........................................................................................... 61 厦门大学博硕士论文摘要库目 录 VII  3.3.5 本节小结 ................................................................................................... 65 3.4 本构方程拟合 ...................................................................................................... 65 3.4.1 介电响应对非线性行为的影响 ............................................................... 65 3.4.2 畴变对非线性行为的影响 ....................................................................... 67 3.4.3 本构方程拟合结果 ................................................................................... 71 3.4.4 本节小结 ................................................................................................... 72 第四章 结论 ................................................................................................... 73 第五章 未来研究及展望 ............................................................................... 75 参考文献 ......................................................................................................... 77 致 谢 ............................................................................................................... 81  厦门大学博硕士论文摘要库厦门大学硕士学位论文 VIII    厦门大学博硕士论文摘要库Degree papers are in the “Xiamen University Electronic Theses and Dissertations Database”. Fulltexts are available in the following ways: 1. If your library is a CALIS member libraries, please log on http://etd.calis.edu.cn/ and submitrequests online, or consult the interlibrary loan department in your library. 2. For users of non-CALIS member libraries, please mail to etd@xmu.edu.cn for delivery details.厦门大学博硕士论文摘要库

In-situ XRD Analysis of Electric Induced Domain Switching in PLZT Ferroelectric Ceramics

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In-situ XRD Analysis of Electric Induced Domain Switching in PLZT Ferroelectric Ceramics

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