ao8b00173_si_001.pdf (2.02 MB)
Download fileCombination of Solid-State and Electrochemical Impedance Spectroscopy To Explore Effects of Porosity in Sol–Gel-Derived BaTiO3 Thin Films
journal contribution
posted on 2018-06-25, 17:34 authored by Joshua Whittam, Andrew L. Hector, Christopher Kavanagh, John R. Owen, Gillian ReidBaTiO3 thin films were
deposited onto polycrystalline
Pt using a dip-coating technique, with annealing temperatures of 750–900
°C. To avoid film imperfections such as cracking or pinholes,
key conditions, including aging periods, water content, and stirring
speeds, were refined to produce a pinhole-free, uniform film with
some porosity. Whereas those coated a single time short circuited
during electrical characterization, this could be avoided in films
produced by multiple coating cycles. The effective permittivity of
a 600 nm BaTiO3 film was measured at 290 by fitting solid-state
impedance data in the frequency range of 100 Hz to 1 MHz. Electrochemical
impedance with an aqueous electrolyte allowed evaluation of the porosity,
which remained fairly constant between 1 and 5 coating cycles. Using
this method, it was possible to estimate the effective permittivity
of the BaTiO3 itself as 374 and hence to evaluate the increase
in the effective permittivity that could be achieved by minimizing
porosity.