H. Qiao, N. Balke
North Carolina State University,
United States
Keywords: ferroelectrics, fatigue, AFM-based technique
Summary:
In many electronic devices, materials are subjected to repeated electrical loading during operation, which leads to a gradual loss of functional properties, ultimately limiting the reliability and service lifetime of devices. This problem is particularly significant for ferroelectric ceramics. When they are repeatedly exposed to electric fields, their polarization, switchability, and piezoelectric coefficients can progressively degrade, which is a phenomenon known as electric fatigue. It remains a long-standing challenge that hinders the development of durable ferroelectric devices. Therefore, understanding of fatigue mechanisms and the factors influencing fatigue behavior is essential for improving material performance and reliability. Most existing studies on electric fatigue rely on macroscopic measurements, which increases the risk of sample damage due to high electric fields. Moreover, conventional macroscopic methods provide little information about local variations in fatigue behavior or how microstructural features influence degradation. To overcome these limitations, we developed a local approach based on atomic force microscopy (AFM) to investigate electric fatigue in ferroelectric ceramics. In this method, an electric field is applied through a conductive AFM tip, allowing localized fatigue tests with minimal risk of damaging the entire sample. Because the affected region is confined to the nanoscale, a series of tests with different electric voltage parameters can be performed on the same sample. Using this technique, we carried out local fatigue experiments with voltages both below and above the local coercive voltage, which is determined by switching spectroscopy piezoresponse force microscopy, and confirmed the feasibility of the approach. The results show that the extent of local fatigue scales with the ratio of the applied field to the local coercive field, enabling the establishment of general relationships that describe the onset of fatigue. Comparison with conventional macroscopic measurements under similar field ratios revealed excellent consistency, demonstrating that the AFM-based method can reliably capture fatigue behavior. This approach provides new opportunities to explore the effects of frequency, temperature, and microstructure on fatigue, and offers valuable insights for the design of ferroelectric materials and devices with improved durability and reliability.