Influence of Structural Phase Transitions on the Mechanical Behavior of Lead-Free Potassium Sodium Niobate Piezoceramics

随着有毒铅基压电陶瓷在各种传感器和致动器中的应用越来越多，环境问题日益严重。在开发无铅替代品方面进行了大量的科学和工业努力，从而确定了各种可能的材料系统。多晶(KxNa1-x)NbO3(KNN)仍然是最有前途的候选材料之一，它具有高居里点、在宽可用温度范围内稳定的机电响应、高的声振动速度和低的密度。尽管在定制机电性能方面取得了许多进展，但在了解机械响应，特别是断裂行为方面的工作很少，这对可靠的商业应用至关重要。在使用过程中，压电陶瓷经常暴露在较高的工作温度和较大的压应力下，用来减少裂纹。因此，本项目的目的是利用德国和中国的综合和互补的实验技术和专业知识，通过各种先进的新测量技术来表征KNN的随温度变化的力学性能和随应力变化的晶体结构。

A growing critical environmental issue exists related to the increasing use of toxic lead-based piezoelectric ceramics for various sensor and actuator applications. There have been substantial scientific and industrial efforts towards the development of lead-free alternatives, which have led to the identification of various potential material systems. Polycrystalline (KxNa1- x)NbO3 (KNN) remains one of the most promising candidates, with a high Curie point, stable electromechanical response over a wide usable temperature range, high acoustic vibration velocities, and low density. Despite the numerous advancements in tailoring the electromechanical properties, there has been very little work on understanding the mechanical response, in particular the fracture behavior, which is crucial for reliable commercial implementation. During operation piezoelectric ceramics are often exposed to high operating temperatures and large compressive stress, used to reduce cracking. Therefore, the aim of this project is to use combined and complementary experimental techniques and expertise in Germany and China to characterize the temperature-dependent mechanical properties and in situ stress-dependent crystal structure of KNN with various advanced novel measurement techniques.