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Comparative Solution Synthesis of Mn Doped (Na,K)NbO 3 Thin Films
Author(s) -
Kovacova Veronika,
Yang Jung In,
Jacques Leonard,
Ko Song Won,
Zhu Wanlin,
TrolierMcKinstry Susan
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202000537
Subject(s) - materials science , microstructure , thin film , fabrication , ferroelectricity , dielectric , current density , crystallization , homogeneity (statistics) , doping , alkali metal , grain size , analytical chemistry (journal) , chemical engineering , mineralogy , nanotechnology , composite material , optoelectronics , chemistry , medicine , statistics , alternative medicine , pathology , quantum mechanics , chromatography , engineering , organic chemistry , physics , mathematics
Abstract (K 0.5 Na 0.5 )NbO 3 (KNN) is a promising lead‐free alternative for ferroelectric thin films such as Pb(Zr,Ti)O 3 . One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non‐stoichiometry. This paper compares three acetate‐based chemical solution synthesis and deposition methods for 0.5 mol % Mn‐doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10 −8 A cm −2 up to electric fields as high as 600 kV cm −1 , which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two‐step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed.