铁酸铋基多铁性材料的制备与电磁性能研究

发布时间：2018-11-13 20:04

【摘要】：磁性材料与电子材料得到越来越广泛的应用,随着科学技术的迅猛发展,更迫切的需要器件的小型化、高度集成化以及多功能化。这种实际应用中的需求导致科研人员们开展越来越多的关于集磁性和电性于一身的这类多功能材料的研究。多铁性材料,它同时拥有多种铁性,而且各种铁性之间可以通过相互耦合协同作用,来实现更多维度的序参量之间的调节,如磁电效应(即材料可以通过改变外磁场大小来调节电极化强度,或者通过改变外电场大小来调节磁极化强度),通过各序参量之间的耦合作用把独立的物理参数磁化强度和电极化强度等可以表征信息的极化矢量紧密地联系起来,这就为磁电功能材料提供了额外可操控的自由度,有望开发新型信息存储功能器件。多铁性磁电耦合材料在新型功能器件以及信息存储器件等领域有着广泛的应用前景。在凝聚态物理中,多铁现象本身就是一个值得研究的问题,它对电学、磁学以及强关联电子体系提出很多挑战,逐渐成为量子调控领域的热点研究问题。BiFeO3是同时在室温以上表现出多铁性的材料体系,因此从2003年至今得到了广泛而深入的研究,并成为推动当前多铁性研究热潮最主要的材料体系。由于高温下Bi易挥发,这会使Fe离子产生变价,导致纯相的BiFe03块材难以制备,并且存在氧空位等缺陷,样品表现出较大的漏电流,一般铁电性能都不理想;另外BiFeO3具有特殊空间调制螺旋结构和倾斜G型反铁磁序,使其呈现室温反铁磁性,这些都严重阻碍其潜在的应用。为了解决这些困难,需要对该类材料进行制备方法的优化或掺杂改性以期望提高BiFeO3陶瓷的电学和磁学性能。本论文针对目前多铁性材料的研究现状,以BiFeO3多铁性材料为基础、主要从制备方法的改进、材料掺杂取代改性以及引入其他钙钛矿结构形成固溶体三个方面开展研究工作,对BiFeO3-BaTiO3固溶体,以及由2BiFeO3-Bi4Ti3O12组成的铋层状Aurivillius结构化合物Bi6Fe2Ti3O18两种材料进行系统的研究,期望增强其铁电性能并在此基础上进一步实现室温铁电、铁磁共存。主要研究工作和取得的成果如下:(1)制备了0.67BiFeO3-0.33BaTiO3固溶体,对其结构、微观形貌、介电、磁性质以及复阻抗等性能进行系统的研究,发现通过淬火工艺可以有效减小0.67BiFeO3-0.33BaTiO3的漏电流,提高体系的铁电性能。(2)制备了 2BiFe03-Bi4Ti3O12层状Aurivillius结构化合物以及Fe位Ni掺杂的样品,系统研究Ni掺杂量对其结构、微观形貌、介电、磁等性能的影响。发现Ni掺杂Bi6Fe2Ti3O18可以有效改善体系的漏电流,并且实现了室温下铁电、铁磁共存。(3)使用电泳沉积法在金属基片上制备了 Bi6Fe2Ti3O18厚膜,对其制备工艺进行了探索,研究了 Bi6Fe2Ti3O18厚膜的微结构和铁电性能。发现厚膜存在致密性的问题,导致漏电流较大而无法获得较好的电滞回线。在此基础上提出了一些可行性的改进方案,后续需要进一步优化制备工艺。
[Abstract]:With the rapid development of science and technology, the magnetic material and the electronic material are more and more widely used. With the rapid development of science and technology, the miniaturization, high integration and multi-function of the device are more and more urgent. The need in this practical application has led to a growing number of research on both magnetic and electrical-based multi-function materials. in that multi-polar material, the multi-dimension material has a plurality of magnetic field at the same time, and can be mutually coupled with each other to realize the adjustment between a more multi-dimensional sequence parameter, such as a magnetoelectric effect (that is, the material can adjust the electric polarization intensity by changing the size of the external magnetic field, or by changing the size of the external electric field to adjust the magnetic polarity strength), the independent physical parameter magnetization and the electric polarization intensity and the like can be closely associated with the polarization vector of the information through the coupling action between the sequence parameters, This provides an additional manipulable degree of freedom for magnetoelectric functional materials and is expected to develop a new type of information storage functional device. The multi-phase magnetoelectric coupling material has a wide application prospect in the fields of novel functional devices and information storage devices and the like. In the condensed matter physics, the phenomenon of multi-iron is a problem to be studied, and it poses a lot of challenges to the electrical, magnetic and strong-associated electronic systems, and has become a hot topic in the field of quantum control. BiFeO3 is one of the most important material systems at the same time at room temperature, so it has been widely and deeply studied since 2003, and has become the most important material system to promote the current multi-channel research. As the Bi is more volatile at high temperature, the valence of the Fe ions can be changed, which leads to the difficult preparation of the BiFe03 bulk material of the pure phase, and the defects such as oxygen vacancy and the like are present, and the sample shows a large leakage current, and the general ferroelectric property is not ideal; in addition, that BiFeO3 has a special space-modulation spiral structure and an inclined G-type anti-ferromagnetic order, so that the BiFeO3 exhibit room-temperature antiferromagnetism, which all seriously hinder its potential application. In order to solve these difficulties, it is necessary to optimize or dope the material to a desired improvement in the electrical and magnetic properties of the BiFeO3 ceramic. Based on BiFeO3 multi-source material, this paper is based on BiFeO3 multi-source material, and mainly studies the three aspects of the preparation method, material doping and modification, and the introduction of other perovskite structure to form a solid solution, and the BiFeO3-BaTiO3 solid solution is prepared. The two materials, Bi6Fe2Ti3O18, which are composed of 2BiFeO3-Bi4Ti3O12 and Bi6Fe2Ti3O18, are studied. The main research work and the results are as follows: (1) The solid solution of 0.67BiFeO3-0.33BaTiO3 is prepared, and its structure, micro-morphology, dielectric, magnetic properties and complex impedance are systematically studied. It is found that the leakage current of 0.67BiFeO3-0.33BaTiO3 can be effectively reduced through the quenching process, and the ferroelectric property of the system can be improved. (2) 2BiFe03-Bi4Ti3O12 layered Auritilius structural compound and Fe-bit Ni-doped sample were prepared, and the effect of Ni doping on its structure, micro-morphology, dielectric and magnetic properties was studied. It is found that Ni-doped Bi6Fe2Ti3O18 can effectively improve the leakage current of the system and realize the coexistence of iron and iron at room temperature. (3) Bi6Fe2Ti3O18 thick film was prepared on the metal substrate by the method of electrophoretic deposition, and the preparation process of Bi6Fe2Ti3O18 was studied. The microstructure and electrical properties of the Bi6Fe2Ti3O18 thick film were studied. it is found that the thick film has a problem of compactness, which leads to a large leakage current and a better electric hysteresis loop can not be obtained. On this basis, some feasible improvement schemes are put forward, and the preparation technology needs to be further optimized.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O482

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