致谢在本论文完成之际,作者首先对导师王月花副教授致以最衷心的感谢,感谢王老师三年来对我工作、学习和生活上的指导、关心及帮助。
本论文是在导师王月花副教授的悉心指导和不断鼓励下完成的,可以说,从论文的选题到论文的完成,每一个环节都倾注了王老师很大的心血。
学术上王老师以身作则,对工作一丝不苟,严谨的治学态度,精益求精的探索精神深深地影响着我。
特别使我难忘的是王老师在百忙之中帮我字斟句酌的修改英文论文,使我的英语写作水平有了很大的提高。
在此,再一次向倾心指导和培养我的王月花副教授致以诚挚的谢意。
在三年的学习中,唐刚教授、韩奎教授、张国营教授、杨先清教授、殷春浩教授、吴玉喜副教授、沈义峰副教授、牟致栋副教授等多位老师也给予了作者很大的帮助。
在这里还要感谢段益峰老师、石礼伟老师和师姐潘红亮,他们的热心帮助使我克服了许多困难。
此外,研究生同学周伟、赵强、胡智向等多位同学曾与作者进行过有益的讨论,在此一并致谢!作者学业的顺利完成离不开家人的帮助和支持,在此也衷心地向他们说一声:谢谢!感谢参与评审的各位老师对我论文的进一步提高提出的宝贵意见。
摘 要ABO 3型钙钛矿材料因其优异的铁电和铁磁特性而受到人们的广泛关注,对于这些特性的微观机理探索也已经成为了一个研究热点。
计算机技术的快速发展使研究真实材料的电子结构成为可能,而密度泛函理论给研究材料的物理性质提供了坚实的理论基础。
因此,基于密度泛函理论的第一性原理计算,就成为研究材料基态性质的强大工具。
通过计算,我们不仅可以解释材料的物理性质,而且可以任意改变材料的形状或所处的环境,从而去模拟不同条件下材料的行为。
这就可以为预测材料的新性能或者指导新材料的合成提供依据。
本文基于密度泛函理论的第一性原理计算方法对ABO 3型掺杂材料x 1-x 3BiAl Ga O 和1-x x 3Y Ca TiO 进行了系统的研究,从电子结构和光学响应方面揭示这些材料的特性。
主要内容如下:一、对正交相x 1-x 3BiAl Ga O 铁电材料的电子特性和光学性质进行了研究。
目前,关于x 1-x 3BiAl Ga O 的研究主要集中在实验合成方面,理论上的报道很少。
为了了解其铁电性以及光学特性与内部电子结构的关系,本文采用第一性原理全势线性缀加平面波方法对x 1-x 3BiAl Ga O 的晶体结构、体模量、能带、态密度及光学响应进行了计算,发现轨道杂化有利于铁电结构的稳定性。
本文还讨论了Al 掺杂浓度对材料性能的影响,并从理论上给出了相应的解释,预言了x 1-x 3BiAl Ga O 是一种可利用的介电材料。
二、本文利用第一性原理全势线性缀加平面波方法对正交相1-x x 3Y Ca TiO 铁磁材料的晶体结构、磁矩、能带、态密度、电子密度分布和光学性质进行了计算。
分析了Ca 掺杂浓度对其磁性以及内部电子结构的影响,并结合实验结果对掺杂后光学性质的变化的机理进行了讨论,得到了一些有意义的结果。
该论文有图16幅,表4个,参考文献59篇。
关键词:x 1-x 3BiAl Ga O ,1-x x 3Y Ca TiO ,第一性原理,电子结构,光学性质AbstractThe ABO 3-perovskites have attracted much interest because of their excellent ferroelectric and ferromagnetic properties, and the explorations of their microscopic mechanism become an active research front. With the development of computer, the computation of electronic structure for practical materials has become available. On the other hand, density function theory gives a firmly theoretical foundation for the study of ground states of materials. Then the first principle calculation based on density function theory has become one of the most powerful tools in condensed matters. With the first principle calculation, we can not only get properties of material, but also simulate their behaviors under different conditions. This means that we can predict the properties of materials or design the required materials.In this thesis, First-principles calculation based on density functional theory are performed for doping-ABO 3 materials x 1-x 3BiAl Ga O and 1-x x 3Y Ca TiO . It is our intention to clarify the properties of these materials by the electronic structure and optical properties. The main contents are as follows:First, the electronic structure and optical properties of orthorhombic x 1-x 3BiAl Ga O are studied. At present, the research are mainly concentrating on experimental synthesis, there is few reports about theory. To find out the relationship between ferroelectric properties and electronic structure, the crystal structure, bulk moduli, energy band, densities of states and optical properties are systematically calculated using the full potential linearized augmented plane wave (FP-LAPW) method. The result shows that orbital hybridizations can help keeping the stability of ferroelectric structure. The effect to the properties with different Al concentration is analyzed and explained in theory. It is proposed that x 1-x 3BiAl Ga O is a promising dielectric material.Second, the crystal structures, magnetic moments, band structures, density of states and charge-density distributions of orthorhombic 1-x x 3Y Ca TiO are calculated using the full potential linearized augmented plane wave method. The effects to the magnetism and electronic structure with different Ca concentration are discussed. Furthermore ,the change of optical properties is analyzed after doping in comparison with the experimental results.Key words: x 1-x 3BiAl Ga O ;1-x x 3Y Ca TiO ; First-Principles; Electronic structure;Optical properties目录摘要 (Ⅰ)目录 (Ⅲ)图清单 (Ⅴ)表清单 (Ⅵ)1 绪论 (1)1.1 物质的铁电性 (1)1.2 物质的磁性 (5)1.3 本文的工作和目的 (11)2 理论基础 (13)2.1 密度泛函理论 (13)2.2 全势线性缀加平面波方法 (19)3 BiAl x Ga1-x O3的电子结构和光学性质 (25)3.1 引言 (25)3.2 计算结果及讨论 (27)3.3 本章小结 (33)4 Y1-x Ca x TiO3的电子结构和光学性质 (35)4.1 引言 (35)4.2 计算结果及讨论 (36)4.3 本章小结 (41)5总结 (43)参考文献 (45)作者简介 (49)学位论文原创性声明 (50)学位论文数据集 (51)Contents Abstract (Ⅰ)Contents (Ⅲ)List of Figures (Ⅴ)List of Tables (Ⅵ)1 Introduction (1)1.1 Ferroelectrics of Materials (1)1.2 Magnetism of Materials (5)1.3 The Work and Purpose of This Thesis (11)2 Theoretical Basis (13)2.1 Density Functional Theory (13)2.2 The Full Potential Linearized Augmented Plane Wave Method (19)3 Electronic Structure and Optical Properties of BiAl x Ga1-x O3 (25)3.1 Introduction (25)3.2 Results and Discussions (27)3.3 Conclusions of the Chapter (33)4 Electronic Structure and Optical Properties of Y1-x Ca x TiO3 (35)4.1 Introduction (35)4.2 Results and Discussions (36)4.3Conclusions of the Chapter (41)5 Conclusions (43)Refere nces (45)Author’s Resume (49)Declaration of Thesis Originality (50)Thesis Data Collection (51)图清单表清单1绪论1绪论1 Introduction1.1 物质的铁电性(Ferroelectrics of Materials)1.1.1铁电性的基本概念铁电晶体是热释电族中的一类晶体,铁电晶体最本质的特征是具有自发极化。