Using crystallographic orientation mapping to examine stress concentrations and local crystallography in piezoelectric materials

使用晶体取向图检查压电材料中的应力集中和局部晶体学

• 批准号: EP/D032768/1
• 负责人: Ian MacLaren
• 金额: $ 15.66万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD032768%2F1
• 关键词: Using; crystallographic; orientation; mapping; examine

Ferroelectric materials such as lead zirconate titanate consist of small domains, each having the electrical polarisation and its associated distortion of the crystallographic unit cell along a different direction. How these domains meet up controls the macroscopic, technologically important properties. Despite their commercial importance, there remains much that is not known about this local crystallography in such materials and how it affects the macroscopic properties. Recent studies by the present applicant have also revealed the presence of large internal stresses around multidomain junctions in such materials, peaking at over 1GPa, and it is clear that such high stress concentrations will have a significant influence on both the piezoelectric properties, as well as the susceptibility to fatigue of a material via microcracking. The ideal method for the determination of the local crystallography and stress concentrations is the generation of crystallographic orientation maps using the automated indexing of Kikuchi diffraction patterns from the transmission electron microscope. Such a methodology has recently become available due to the computerisation of TEM control software, and the development of software for the automatic indexing of Kikuchi patterns. The wealth of information from the resulting orientation maps will be used to determine local crystallographic parameters including unit cell distortion and for phase identification in multiphase compositions, as well as the quantification of stress concentrations at specific points in the microstructure. The resulting data will then be discussed with the materials manufacturers in order to understand how the local crystallography and local stress concentrations are affecting the piezoelectric properties of materials and their mechanical fatigue behaviour on extended electromechanical cycling.

诸如锆钛酸铅的铁电材料由小的畴组成，每个畴具有沿沿着不同方向的晶体学晶胞的电极化及其相关联的畸变。这些领域如何相遇控制着宏观的、技术上重要的性质。尽管它们在商业上很重要，但关于这种材料中的局部晶体学以及它如何影响宏观性质仍然有很多未知之处。本申请人最近的研究还揭示了在这种材料中的多畴结周围存在大的内应力，峰值超过1GPa，并且很明显，这种高应力集中将对压电性能以及材料经由微裂纹的疲劳敏感性两者产生显著影响。确定局部晶体学和应力集中的理想方法是使用透射电子显微镜的菊池衍射图案的自动索引生成晶体学取向图。由于TEM控制软件的计算机化以及用于自动索引菊池图案的软件的开发，这种方法最近变得可用。丰富的信息，从所得的取向图将被用来确定当地的晶体学参数，包括晶胞畸变和多相组合物中的相识别，以及在微观结构中的特定点的应力集中的量化。然后将与材料制造商讨论所得数据，以了解局部晶体学和局部应力集中如何影响材料的压电性能及其在扩展机电循环中的机械疲劳行为。