1、山东大学硕士学位论文i物理学院凝聚态物理副教授高温铋层状结构 SrBi4Ti4O15 压电陶瓷的性能及温度稳定性研究Piezoelectric properties and thermal stabilities of high temperature bismuth layer-structured ferroelectric SrBi4Ti4O15 ceramics山东大学硕士学位论文ii目录摘要 .IABSTRACT .III符号说明 .V第一章 绪论 .11.1 引言 .11.2 铋层状结构无铅压电陶瓷的研究现状 .21.2.1 铋层状结构材料的结构特点 .21.2.2 铋层状结构材料
2、的物理性质 .31.3 提高铋层状结构材料压电性能的方法 .41.4 本论文研究的内容 .5第二章 材料制备及测试 .62.1 材料的制备 .62.2 材料的测试分析手段 .102.2.1 介电压电性能测量 .102.2.2 材料的表征分析 .11第三章 A 位 Ce 取代对 SrBi4Ti4O15 压电性能的影响 .123.1 引言 .123.2 样品的制备与测试 .133.3 实验结果和讨论 .133.3.1 X 射线衍射分析 .133.3.2 介电性能 .143.3.3 铁电性能 .173.3.4 压电性能 .183.3.5 高温机电性能 .203.4 本章小结 .22第四章 B 位 C
3、o 取代对 SrBi4Ti4O15 结构和性能的影响 .234.1 引言 .234.2 样品的制备与测试 .234.3 实验结果和讨论 .244.3.1 X 射线衍射分析 .244.3.2 铁电性能 .254.3.3 介电、压电性能 .264.3.4 高温机电性能 .284.4 本章小结 .30山东大学硕士学位论文iii第五章 B 位 Mn 取代对 SrBi4Ti4O15 结构和性能的影响 .315.1 引言 .315.2 样品的制备与测试 .315.3 实验结果和讨论 .325.3.1 X 射线衍射分析 .325.3.2 铁电性能 .335.3.3 介电、压电性能 .345.3.4 高温机电
4、性能 .375.4 本章小结 .38第六章 总结与展望 .396.1 总结 .396.2 展望 .40参考文献 .41致谢 .46发表的论文 .48山东大学硕士学位论文ivCONTENTSABSTRACT(in Chinese) .IABSTRACT(in English) .IIISymbol list .VChapter 1 Introduction .11.1 Introduction .11.2 Bismuth layer-structured ferroelectric (BLSF) piezoelectric ceramics .21.2.1 Structure of BLSFs.
5、21.2.2 Physical properties of BLSFs .31.3 Piezoelectric properties of BLSFs .41.4 Contents of this thesis .5Chapter 2 Experimental procedure.62.1 Preparation .62.2 Material test and analysis methods.102.2.1 Dielectricity and piezoelectricity test .102.2.2 Characterization analysis.11Chapter 3 Effect
6、s of A-site Ce substitution on the piezoelectric properties of SrBi4Ti4O15 ceramics .123.1 Introduction .123.2 Experimental procedure .133.3 Experimental results and discussion .133.3.1 X-ray diffraction analysist.133.3.2 Dielectric properties .143.3.3 Ferroelectric properties.173.3.4 Piezoelectric
7、properties .183.3.5 Electromechanical properties at elevated temperature .203.4 Conclusions .22Chapter 4 Effects of B-site Co substitution on the piezoelectric properties of SrBi4Ti4O15 ceramics .234.1 Introduction .234.2 Experimental procedure .234.3 Experimental results and discussions .244.3.1 X-
8、ray diffraction analysist.244.3.2 Ferroelectric properties.254.3.3 Dielectric and piezoelectric properties .26山东大学硕士学位论文v4.3.4 Electromechanical properties at elevated temperature .284.4 Conclusions .30Chapter 5 Effects of B-site Mn substitution on the piezoelectric properties of SrBi4Ti4O15 ceramic
9、s .315.1 Preface.315.2 Preparation and testing of the sample.315.3 Experimental results and discussions .325.3.1 X-ray diffraction analysist.325.3.2 Ferroelectric properties.335.3.3 Dielectric and piezoelectric properties .345.3.4 Electromechanical properties at elevated temperature .375.4 Conclusio
10、ns .38Chapter 6 Summary and future outlook .396.1 Summary .396.2 Future outlook .40References.41Acknowledgements .46List of publications.48山东大学硕士学位论文I摘要铋层状结构铁电体具有较大的自发极化、良好的抗疲劳性能和较高的居里温度，因此在铁电存储和高温压电方面具有广泛的应用前景。铋层状结构铁电体的铁电性主要来源于铋氧层(Bi 2O2)2+之间的类钙钛矿层中的 B 位阳离子的偏移、氧八面体沿 c 轴的倾侧以及八面体在 a-b 面内的旋转，但是由于其自发极化
11、的旋转受到晶体结构的限制，只能在 a-b 二维平面内转动，使得铋层状结构铁电材料难以极化，压电活性较低。目前，对铋层状结构铁电体在高温压电方面的研究主要是：在维持高居里温度的前提下，通过提高烧结密度、增加电阻率、提高剩余极化、降低矫顽场等手段来提高其压电活性。本论文选择居里温度 Tc=521 OC，压电常数 d33=15 pC/N 的铋层状结构压电材料钛酸铋锶SrBi4Ti4O15 (SBT)作为研究对象，采用传统的固相烧结工艺对其进行组分优化研究，以期获得压电性能优良，又能保持较高居里温度的高温铋层状结构压电材料。本论文首先采用适合于十二配位的 Ce 离子对 SrBi4Ti4O15 的 A
12、位 Sr 离子进行取代改性研究，表达式为 Sr1-xCexBi4Ti4O15。研究结果显示 Ce 对 Sr 的取代降低了烧结温度，同时提高了陶瓷材料的致密度，并且显著降低了 SBT 材料的矫顽场，使得材料更容易被极化。当 x=0.04 时，SBT 系列陶瓷的压电性能得到显著提高，压电常数 d33 达到 27 pC/N，介电损耗显著降低。改性后的 SBT 压电陶瓷的平面机电耦合系数 kp，频率常数 Np 和 Nt 具有优异的温度稳定性，从室温到 475 OC 的温度范围内， kp 在 5%附近变化，N p 和 Nt 的温度变化率分别为68 ppm/K 和25 ppm/K。随着温度的增加(室温至
13、475 oC)，串联谐振频率基频 fs0 和并联谐振频率基频 fp0 几乎线性地降低，其温度变化率均为 68 ppm/K。改性后的材料抗热老化性能好，在高温下保持较高的压电性。在研究 A 位离子取代改性的同时，我们还研究了 B 位离子取代对SrBi4Ti4O15 压电陶瓷电学性能的影响，本论文选用了 Co 离子和 Mn 离子分别取代 B 位的 Ti 离子。X 射线衍射图谱分析显示，取代后的样品为纯的铋层状结构铁电体（m=4）的正交相 。随着 Co 含量的提高， SrBi4Ti4-yCoyO15 压电陶瓷的烧结温度显著降低，样品致密度得到增加，居里温度 Tc 略有上升。经过 Co 取代山东大学硕
14、士学位论文II后，材料的压电活性提高，当 y=0.03 时，SrBi 4Ti4-yCoyO15 系列陶瓷的改性效果最为显著，压电常数 d33 达到 28 pC/N，说明 Co 对 B 位 Ti 的取代也能显著提高SBT 压电陶瓷的压电性能压电常数。在 Mn 取代 B 位 Ti 的研究中，我们发现Mn 和 Co 具有同样的压电性能改善效果。结果显示 Mn 对 Ti 的取代(SrBi 4Ti4-zMnzO15)降低了烧结温度，改善了样品致密度，降低了介电损耗，增强了压电性能，提高了居里温度 Tc。当 z=0.04 时，SBT- zMn 系列陶瓷的性能改性效果最为显著，压电常数 d33 达到 30
15、pC/N。高温电学性能测试表明 Mn 取代改性的SBT 压电陶瓷，其介电、压电性能具有优异的温度稳定性。关键词：钛酸锶铋(SrBi 4Ti4O15)；铋层状结构铁电体 ；压电陶瓷；温度稳定性；电滞回线；机电耦合特性山东大学硕士学位论文IIIABSTRACTBismuth layer-structured ferroelectric materials (BLSF) can have wide applications in high temperature piezoelectrics and ferroelectric memory owing to their good fatigue r
16、esistance and high Curie temperatures. The ferroelectricity of BLSF materials mainly comes the deviation of B cations in the perovskite layer, the tilting of octahedron along the c-axis and the rotation of octahedron in the a-b plane between (Bi2O2)2+ layers. The spontaneous polarization of BLSF mat
17、erials can only rotate inside the a-b plane due to the limit of the layered structure and thus the material is hard to polarize and its piezoelectric property is poor. Research on BLSF mainly focused on how to improve their piezoelectric activity by increasing their density, resistivity as well as t
18、heir remnant polarization and reducing their coercive field while keeping their Cuire temperature unchanged. Layered-structured SrBi4Ti4O15 ceramics with Curie temperature Tc 521OC，d 33=15pC/N was chosen in this study, traditional solid-phase sintering process its doping research in order to get exc
19、ellent piezoelectric properties while maintaining a high Curie temperature.In this thesis, using suitable dodecahedron with a bit of Ce ions replaces SrBi4Ti4O15 A-site Sr ions substituted replace modification. The results showed that Ce Sr substitution reduces the sintering temperature, while incre
20、asing the density of the ceramic material, and significantly reduces the coercive field of the SBT material, such material is more likely to be polarized. For Sr1-xCexBi4Ti4O15 ceramics, when x=0.04, the modification effect SBT most significant Ceramic piezoelectric constant d33 reaches 27pC/N, diel
21、ectric loss is significantly reduced. SBT bismuth layered structure of piezoelectric ceramic planar electromechanical coupling coefficient of the modified kp, radial stretching vibration mode frequency constant Np and thickness extension vibration mode frequency constant Nt with increasing temperatu
22、re changes relatively stable, from room temperature to a temperature within the range of 475 OC kp 5% variation in the vicinity of the temperature change rate of Np and Nt are -68 ppm / K and -25 ppm / K. As the temperature increases (from room temperature to 475 OC),the fundamental frequency of the series resonant fs0, paralle
