【作者】 陈涛；

【导师】 丁士华；

【作者基本信息】 西华大学 ， 材料学， 2008， 硕士

【摘要】 钛酸钡（BaTiO₃）是一种具有钙钛矿结构（ABO₃）的介电材料，由于具有铁电、压电、高介电常数和正温度系数效应等优异的电学性能，是高介电陶瓷电容器的主要原材料。并且钛酸钡系列的弛豫铁电陶瓷由于其极高的介电常数、相变温度和弛豫化的相变行为等优良特性，成为多层陶瓷电容器必不可少的介质材料。因此，研究具有弛豫性能的BaTiO₃陶瓷已引起人们极大的研究兴趣。本论文采用固相反应法制备了Ba(Ti_0．91Zr_0.09)O₃陶瓷，结合实验结果探讨了掺杂对Ba(Ti（0．91）Zr_0.09)O₃陶瓷的烧结特性、介电弛豫特性、相变特性以及材料的铁电、压电性质的影响。主要内容为：1．研究了CuO-BaO混合物的液相烧结特性。研究发现，无论在预烧前和预烧后添加CuO-BaO（Cu／Ba=2．5）混合物能有效降低陶瓷烧结温度，但是预烧前加入发现在斜方-四方相变峰处有弛豫现象出现。改变Cu／Ba比，斜方-四方、四方-立方相变峰变得平坦，弛豫现象更加明显。电滞回线呈现典型弛豫铁电体的特征，压电性能研究发现陶瓷的压电系数随晶粒尺寸的增大而增大。2．研究了不同氧化物（A位：Bi₂O₃，Li₂O．B位：CuO，MoO₃，Al₂O₃）掺杂对Ba(Ti_0.91Zr_0.09)O₃陶瓷的介电性能的影响。根据电荷平衡，A位或B位异价掺杂会导致缺陷的产生。研究发现，当掺杂量较大时，陶瓷材料出现了明显的频率色散和弥散相变，因此它们属于弛豫铁电体，并且随着掺杂量的增加，弛豫的程度也加大。弛豫的原因是异价掺杂离子的电价、离子半径，极化率的不同导致材料内部无序度增加，产生局域应变，局域应变又诱发极性微区形成的。3．研究了AB位共掺（Bi-Al，Li-Mo）对Ba(Ti_0．91Zr_0．09)O₃陶瓷的介电性能的影响。发现共掺后，陶瓷更容易从正常铁电体转变为弛豫铁电体，原因是A，B位同时掺杂后，A位，B位及AB位协同作用将增加无序的程度，更容易诱发极性微区形成弛豫现象。更多还原

【Abstract】 Barium titanate（BaTiO₃） is a dielectric material, with a perovskite （ABO₃） structure, it is the primary material for high dielectric constant ceramic capacitors due to its excellent electronic performance, such as ferroelectric, piezoelectric, high dielectric constant and positive temperature coefficient effect, etc. And relaxor ferroelectrics based on BaTiO₃ are important dielectric of multilayer ceramics capacitor because of their large permittivity, phase transition temperature and relaxor phase transition behavior. Therefore, for its many applications in electronic devices, the study of relaxor property on BaTiO₃ ceramic has attracted a considerable amount of researchers’ interesting.In this thesis, Ba(Ti_0.91Zr_0.09)O₃ ferroelectric ceramics are prepared by a traditional solid phase reaction. Sintering characteristic, phase transition and ferroelectric, piezoelectric properties of Ba(Ti_0.91Zr_0.09)O₃ ceramics doped with additive have been investigated. The main results are as follows:1. Sintering characteristic of Ba(Ti_0.91Zr_0.09)O₃ ceramics are investigated for CuO-BaO mixture addition. The results showed that in spite of pre-calcined or post-calcined Ba(Ti_0.91Zr_0.09)O₃, CuO-BaO additives can lower the sintering temperature, but dielectric relaxor properties is observed at orthorhombic -tetragonal phase transition point for pre-calcined Ba(Ti_0.91iZr_0.09)O₃ with CuO-BaO addition. With increasing of Cu/Ba ratio, orthorhombic-tetragonal and tetragonal-cubic dielectric phase transition peak becomes flat, relaxation phenomenon is obviously observed. The polarization hysteresis loops exhibits a typical relaxor ferroelectric behavior. The research on piezoelectric properties discovers that piezoelectric coefficients increase with increasing grain size.2. The effect of doped with diversity oxide （A-site: Bi₂O₃, Li₂O, B-site: CuO, MoO₃, Al₂O₃） on dielectric property of Ba(Ti_0.91Zr_0.09)O₃ ceramics are investigated. According to charge balance principle, the defects are induced by A-site or B-site heterovalent substitute for Ba(Ti_0.91Zr_0.09)O₃ ceramics. The results show that the samples became relaxor ferroelectric when rather large doping contents. And with the increasing of doping content, the phase transition became more relaxed. The different valence, radius and polarization of heterovalent ion substitution in the material lead to increase disorder and create local-strain. This could be attributed to polar nanoregions which are brought by local-strain.3. The effect of cationic substitution of A and B-site （Bi-Al, Li-Mo） for Ba(Ti_0.91Zr_0.09)O₃ ceramics on dielectric property are investigated. The evolution from a normal ferroelectric to a relaxor ferroelectric is easily observed for A and B-site codoped. The more polar nanoregions induced by A and B-site co-doping, the more easily relaxor property occurred,更多还原