abstract
If piezoelectric thin films sensors based on K0.5Na0.5NbO3 (KNN) are to achieve commercialization, it is critical to optimize the film performance using low-cost scalable processing and substrates. Here, sol-gel derived KNN thin films are deposited using a solution with 5% of potassium excess on Pt/TiO2/SiO2/Si and Pt/SrTiO3 substrates, and rapid thermal annealed at 750 degrees C for 5 min. Despite an identical film morphology and thickness of similar to 335 nm, an in-plane stress/strain state is found to be tensile for KNN films on Pt/TiO2/SiO2/Si, and compressive for those on Pt/SrTiO3 substrates, being related to thermal expansion mismatch between the substrate and the film. Correspondingly, KNN films under in-plane compressive stress possess superior dielectric permittivity and polarization in the parallel-plate-capacitor geometry.
keywords
ELECTRICAL-PROPERTIES; THERMAL-EXPANSION; CERAMICS; SRTIO3
subject category
Materials Science
authors
Tkach, A; Santos, A; Zlotnik, S; Serrazina, R; Okhay, O; Bdikin, I; Costa, ME; Vilarinho, PM
our authors
André Pereira dos Santos
Research Fellowship
Maria Elisabete Jorge Vieira Costa
Collaborator
Oleksandr Tkach
Assistant Researcher
Olena Okhay
Post-Doc Fellowship
Paula Maria Lousada Silveirinha Vilarinho
Vice Director
Ricardo Serrazina
PhD Student
Sebastian Zlotnik
Post-doc Fellowshipacknowledgements
This work was funded by FEDER funds via Programa Operacional Factores de Competitividade-COMPETE and National funds via FCT (Fundacao para a Ciencia e a Tecnologia) within the Project CICECO-FCOMP-01-0124-FEDER-037271 (FCT PEst-C/CTM/LA0011/2013) as well as within FCT independent researcher grants (IF/00602/2013 and IF/00582/2015).