稀土掺杂BiFeO3陶瓷的制备和电学性能表征
毕业论文关键词 铁电体 BiFeO3 基 A 位 Sm掺杂 快速烧结 介电性
Title The Preparation and Characterization Of Rare-earth-element doped BiFeO3 Ceramics
Abstract As an important kind of dielectric materials，ferroelectric materials are characterized by high dielectric constant, remarkable pyroelectric and piezoelectric effects. This paper mainly describes the BiFeO3-based ceramic materials as ferroelectric. BiFeO3 is a very special ferroelectric material which has both long-range magnetic ordering and ordered long-range polarization. Its main advantage lies in its high ferroelectric Curie temperature and high magnetic transition temperature. A-site and B-site doped ceramics possess better properties via modulation of the crystal structure. In this paper, Bi1-xSmxFeO3 ceramic samples with a variety of components were prepared by the rapid liquid-phase sintering method. X-ray and Raman spectra were used in analyzing the crystal structure to confirm that Bi1-xSmxFeO3 ceramics have a rhombohedral-to-orthorhombic phase transition at the Sm component of ~0.125-0.2. Ferroelectric and dielectric properties of the samples were measured, which revealed that the introduction of certain Sm3+ enhanced the saturated polarization Ps and d33 values. At last, The pizeoelectric properties in poled Bi1-xSmxFeO3 at various temperatures show the existence of ferroelectric phase below 700℃.
Keywords Ferroelectric A-site doped BiFeO3 Rapid Sintering Dielectric Property
目次
1引言1
1.1铁电材料概述..1
1.2BiFeO3概述4
1.3掺杂改性对BiFeO3陶瓷的性能影响.9
1.4本文研究的内容和意义..10
2Bi1-xSmxFeO3陶瓷的制备及测试..11
2.1制备系统与测试系统11
2.2快速液相烧结法简介12
2.3Bi1-xSmxFeO3陶瓷的制备工艺14
2.4性能测试..15
3Bi1-xSmxFeO3陶瓷的结果与分析..17
3.1X射线衍射分析..17
3.2拉曼光谱分析19
3.3Bi1-xSmxFeO3系列陶瓷的电学性能.21
结论25
致谢26
参考文献..27
1 引言 铁电材料作为一类重要的电介质材料，具有较高的介电常数，显著的热释电和压电效应，广泛应用于从日常生活到尖端技术的多个领域。以铁酸铋(BiFeO3)为基的陶瓷材料作为一种性能优秀的无铅铁电材料，是当前国际上铁电研究领域中的热点之一。铁酸铋在室温下同时具有铁电有序 (TC = 1103K)和 G型反铁磁有序 (TN = 643 K) ,是少数室温下同时具有铁电性和磁性的铁磁电材料之一[1]。然而纯铁酸铋陶瓷存在电极化不大、二级磁电耦合效应微弱等不足，通过A位、B位离子掺杂来调整铁酸铋基陶瓷晶体结构，针对铁电性、反铁磁性等特征进行掺杂改性，以获得更优秀的性能。 1.1 铁电材料概述 1.1.1 铁电材料的定义 铁电物理的研究一直是一个十分活跃的领域，它所研究的对象——铁电材料是这样的一类晶体： 在有限温度下具有自发极化， 而且自发极化有两个或多个可能的取向，在电场作用下其取向是可以改变的。 极化交互作用会导致长程有序与热涨落(温度 T)竞争，一旦前者强度超过后者就会发生顺电-铁电相变，反之亦然[2-6]。由于极化是一种极性矢量，自发极化的出现在晶体中造成一个特殊的方向，每个晶胞中的原子会沿着该方向产生相对位移，使得正负电荷的中心不重合，形成电偶极矩。根据对晶体对称性的分析，很容易知道铁电材料具有铁电性(ferroelectricity)的同时，也具有热电性 (pyroelectricity)和压电性 (piezoelectricity) [5-7]。