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

有毒的铅基压电陶瓷越来越多地用于各种传感器和执行器应用，这是一个日益严重的环境问题。在开发无铅替代品方面，科学界和工业界已经做出了大量努力，从而确定了各种潜在的材料体系。多晶（KxNa1- x）NbO3 （KNN）仍然是最有希望的候选材料之一，具有高居里点，在广泛的可用温度范围内稳定的机电响应，高声波振动速度和低密度。尽管在定制机电性能方面取得了许多进步，但在理解机械响应方面的工作却很少，特别是断裂行为，这对于可靠的商业应用至关重要。在工作过程中，压电陶瓷经常暴露在高工作温度和大压应力下，用于减少开裂。因此，该项目的目的是利用德国和中国的结合和互补的实验技术和专业知识，通过各种先进的新型测量技术来表征KNN的温度依赖性机械性能和原位应力依赖性晶体结构。

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.