Reaction mechanisms of ethylenediaminetetraacetic acid and diethanolamine in the precursor solution for producing (K, Na)NbO3 thin films with outstanding piezoelectric properties
Goh, Phoi Chin
Date of Issue2012
School of Materials Science and Engineering
An understanding of the reaction mechanisms of ethylenediaminetetraacetic acid (EDTA) and diethanolamine (DEA) for producing solution-derived (K, Na)NbO3 (KNN) thin films with outstanding piezoelectric properties and low leakage current is developed. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR) were used to analyze the interactions among EDTA, DEA, and metal cations in both precursor solutions and amorphous films. XPS analyses showed that the oxidation states of potassium, niobium, and oxygen in KNN amorphous film were enhanced with addition of EDTA and DEA in the precursor solution, which shifted closer to the oxidation states in the perovskite phase of the resulting KNN oxide film. FTIR analyses indicated that EDTA and DEA formed dative bonds with the nonhydrated potassium and sodium acetate after pyrolysis process at 330 °C while NMR analyses showed that such interactions could have occurred in the precursor solution. NMR analyses also indicated that DEA could have chelated niobium precursor. It is proposed that EDTA and DEA acted as a “bridge” that linked the metal precursors in the solution, which is critical to suppressing the volatilization of the metal cations, for achieving the reported outstanding electrical properties of the resulting KNN films.
The journal of physical chemistry C