KNN-based piezoelectric materials: Characterization and engineering approaches

Piezoelectric materials are known for their ability to convert mechanical energy into electrical energy and vice versa, making them crucial in a variety of applications. These include ultrasonic devices, micro and nano positioning systems, and providing small-scale energy for electronic devices like sensors. One notable group of materials, ceramic oxides based on (K,Na)NbO3, has garnered significant attention, despite ongoing challenges in enhancing their performance.
This thesis presented (K,Na,Li)(Nb,Sr)O3 ceramics doped with BaZrO3 and (Ba,Ca)ZrO3 as an alternative to improve piezoelectric and ferroelectric properties of undoped (K,Na)NbO3 ceramics. Essential to this research was the characterization of these ceramics, focusing on piezoelectric coefficients critical for finite element analysis to evaluate their suitability as sensors or energy harvesters.
Experimentally, it was investigated three engineering applications: as sensors, subjected to various mechanical loads to assess voltage output and repeatability; as actuators, evaluating ferroelectric properties and deformation under an applied electric field, including fatigue responses after thousands of cycles; and as energy harvesters, utilizing vibrations with cantilever support.
In addition, (K,Na,Li)(Nb,Sr)O3 thin films doped with (Ba,Ca)ZrO3, fabrication and characterization were driven by the need for miniaturization in electronic components. Initial findings show promising piezoelectric and ferroelectric behaviors at the microscale, underscoring the potential of these compositions through optimized fabrication processes and thorough property assessments.
This research provides insights into dopant use, fabrication design, and engineering strategies for piezoelectric and ferroelectric oxides, aiming to guide future applications in electronic miniaturization and beyond.