热压烧结PLZT透明电控光散射陶瓷的各向异性研究

发布时间：2018-05-15 08:48

本文选题：PLZT透明陶瓷 + 电控光散射　；参考：《上海应用技术大学》2017年硕士论文

【摘要】：镧掺杂锆钛酸铅(简称PLZT)陶瓷是一类具有优异性能并能在电、磁、光、力和热等之间相互耦合的铁电压电材料。除了具有一般材料的铁电压电性能外,它还具有非常高的光学透过率和独特的电光效应:一、在可见光及至近红外线范围内,光学透过率可达到70%以上;二、优异的电控双折射效应,即在外电场调控下,通过样品的入射光双折射率“可控”,从而实现对入射光的调制;三、独特的电控光散射效应,即在外电场调控下,通过样品的入射光发生很强的散射,从而实现对光的任意调制。为了应对由现代激光技术的迅猛发展所带来的对激光的屏蔽、衰减、防护等的巨大挑战,人们开发了无需使用偏振系统的、基于PLZT电控光散射效应的光学元器件。但PLZT陶瓷的电控光散射行为受材料组成、热压烧结(施加压力)及陶瓷内应力等的影响较大,故本论文从材料的组成设计着手,经过对材料的热压烧结,成品的退火处理等方面,系统地研究PLZT透明电控光散射陶瓷的物理各向异性及其退火效应。为了研究PLZT材料在不同方向上的各向异性,采用通氧热压烧结工艺,制备出了结构致密、成分均匀的PLZT(X/70/30, X=7.45、7.51、7.57、7.63)系列透明陶瓷。系统地研究了该系列材料在平行于热压方向和垂直于热压方向上的相结构、微观结构及相关性能:在热压烧结过程中,各组分陶瓷样品均形成了纯钙钛矿结构及稠密、均匀的晶粒;La元素可以有效地促进晶粒长大、提高材料的光学透过率,优化材料的电控光散射性能;在平行于热压方向上,四方比(c/a1)更偏离菱方(c/a=1)、单胞体积更小,结构畸变更严重;同时,由于热压烧结过程中,平行于热压方向的阻力(压力)更大,使得该方向上的平均晶粒尺寸略小;在平行于热压方向上,更严重结构畸变、更多的晶界使得该方向上光散射损失严重,光学透过率低于垂直于热压方向上的透过率;在平行于热压方向上,材料展现了更稳定、更优异的电控光散射性能。采用通氧热压烧结工艺,制备出结构致密、成分均匀的PLZT(X/70/30,X=7.45、7.54、7.63)系列透明陶瓷。在基于PLZT陶瓷材料各向异性研究的基础上,选取“平行”切割样品,针对平行于热压方向上的性能,研究了退火处理对PLZT陶瓷性能的影响:没有进行退火处理时,各组分陶瓷样品均呈现出典型的饱和方形电滞回线,退火处理后,PLZT陶瓷的剩余极化Pr和矫顽场Ec均明显地减小,尤其是PLZT(7.63/70/30)组分陶瓷呈现出了具有反铁电特性的双细电滞回线特征。与材料铁电性相对应的场致应变,在退火处理后明显地缩小。由于陶瓷的光学和电光性能对退火条件非常敏感,故此将退火处理细分为快退火和慢退火。各成分陶瓷经过退火处理后,材料的光学透过率增加,且慢退火处理的样品透过率比快退火增加的更多。退火处理后,各组分陶瓷样品的电控光散射性能均得到较大的提高,尤其是PLZT(7.63/70/30)组分陶瓷样品表现出了不同的电控光散射行为——透过率在较低的阀值电场下达到最大值,并且能够在较宽的电场范围内保持最大值和完美的对称性。
[Abstract]:Lanthanum doped lead zirconate titanate (PLZT) ceramics is a class of ferroelectric materials with excellent properties and can be coupled to electricity, magnetism, light, force and heat. Besides the iron voltage and electrical properties of general materials, it has very high optical transmittance and unique electro-optical effect. One, light and near infrared range, light The transmission rate can reach more than 70%; two, the excellent electronic control birefringence effect, which is controlled by the external electric field, can be modulated by the incident light birefringence of the sample, thus realizing the modulation of the incident light; three, the unique electronic electronic light scattering effect, that is, the incident light of the sample is strongly scattered under the control of the external electric field, and thus the light is realized. In order to cope with the great challenge of laser shielding, attenuation and protection brought by the rapid development of modern laser technology, people have developed optical components without using the polarization system, based on the PLZT electronic light scattering effect. However, the electronic light scattering behavior of PLZT ceramics is composed of materials, hot press sintering (exerting pressure) In this paper, the physical anisotropy and annealing effect of PLZT transparent electronic light scattering ceramics are systematically studied by hot pressing sintering of materials and annealing treatment of finished products. In order to study the anisotropy of PLZT materials in different directions, the oxygen heat is used in this paper. PLZT (X/70/30, X=7.45,7.51,7.57,7.63) series transparent ceramics with compact structure and uniform composition are prepared by pressure sintering process. The phase structure, microstructure and related properties of this series of materials are systematically studied in the direction of hot pressing and perpendicular to the hot pressing direction. In the process of hot pressing, the samples of each component are pure. Perovskite structure and dense, uniform grain, La element can effectively promote grain growth, improve the optical transmittance of the material and optimize the electronic light scattering properties of the material. In the direction of parallel to the hot pressure, the square ratio (c/a1) is more deviated from the rhombus (c/a=1), the cell volume is smaller, and the structural modification is serious. At the same time, due to the hot pressing sintering process, parallel. The resistance (pressure) is greater in the direction of the hot press, which makes the average grain size in the direction slightly smaller; in parallel to the direction of the hot press, more serious structural distortion, more grain boundaries make the light scattering loss in this direction serious, the optical transmittance is lower than the transmissivity perpendicular to the hot pressing direction, and the material is more stable in the direction parallel to the hot pressing direction. PLZT (X/70/30, X=7.45,7.54,7.63) series of transparent ceramics with dense structure and uniform composition were prepared by hot pressing sintering process. Based on the study of anisotropy of PLZT ceramics, the "parallel" cutting samples were selected and annealed in parallel to the properties of the hot pressing direction. The effect of treatment on the properties of PLZT ceramics: the ceramic samples of each component showed a typical saturated square hysteresis loop without annealing treatment. After annealing, the residual polarization Pr and the coercive field Ec of the PLZT ceramics decreased obviously, especially the PLZT (7.63/70/30) component ceramics showed a double hysteresis loop with antiferroelectric properties. Characteristics. The field induced strain corresponding to the ferroelectric properties of the material is obviously reduced after annealing. As the optical and electro-optical properties of the ceramics are very sensitive to the annealing conditions, the annealing treatment is subdivided into fast annealing and slow annealing. After annealing, the transmittance of the materials is increased, and the sample through the annealing process is slowly annealed. After annealing treatment, the electronic light scattering properties of each component of the ceramic samples were greatly improved, especially the PLZT (7.63/70/30) component ceramics showed different electronic light scattering behavior - the transmittance reached the maximum under the lower threshold electric field and could be in a wider electric field range. The maximum and perfect symmetry are maintained within.

【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ174.1

【参考文献】