ISBN 9783843949729

978-3-8439-4972-9, Reihe Anorganische Chemie

Anjneya Verma
Piezoelectric Alkali Metal Niobates and Tantalates as Lead-Free Vibrational Energy Harvesters

178 Seiten, Dissertation Universität Köln (2021), Softcover, A5

Zusammenfassung / Abstract

The piezoelectric films of pure and A, B site substitutionally doped (K,Na)NbO3 (KNN) and LiTaO3 (LTO) were synthesized as cantilevers, uni-morphs, bi-morphs, and patches. These lead-free piezoelectric materials were deposited on various substrates as thick films and fabricated into piezoelectric energy harvesting devices. The structural, ferroelectric, pyroelectric, piezoelectric, dielectric properties, and device performances of piezo elements and devices were systematically investigated for their application as energy harvesters to self-power sensors in the automotive.

Homogenous piezoelectric films are required to achieve high electromechanical energy with a sufficiently large piezoelectric constant. For this purpose, the effect of film thickness on piezoelectric and dielectric performance was investigated. Furthermore, the effect of poling on piezoceramics was studied to optimize the piezoelectric response and power output. The phase-voltage and butterfly curves using the piezo force microscopy proved the great ferroelectric and piezoelectric response of the lead-free devices. Moreover, the permittivity, leakage current, and FOM of the devices were examined to determine the best conditions for energy harvesting applications. Given the need for lead-free piezoelectric devices, KNN and LTO-based piezoceramics are promising alternatives due to their repeatable properties, cost-effectiveness, and power output in a variable frequency range, which makes them suitable for MEMS energy harvesters for various applications.