Electric double layer formed by polarized ferroelectric thin films.

TitleElectric double layer formed by polarized ferroelectric thin films.
Publication TypeJournal Article
Year of Publication2013
AuthorsRJ Ferris, S Lin, M Therezien, BB Yellen, and S Zauscher
JournalAcs Applied Materials & Interfaces
Start Page2610
Pagination2610 - 2617
Date Published04/2013

Ferroelectric surfaces can have very high surface charge densities that can be harnessed for manipulation of charged colloidal particles and soft matter in aqueous environments. Here, we report on the electrical double layer (EDL) formed by polarized ultrasmooth lead zirconium titanate (US-PZT) thin films in dilute electrolyte solutions. Using colloidal probe force microscopy (CPFM) measurements, we show that the ion distribution within the double layer can be changed by reversing the ferroelectric polarization state of US-PZT. The interaction force in dilute 1:1 electrolyte solution between the negatively charged probe and a positive surface charge (upward polarized) US-PZT thin film is attractive, while the interaction force is repulsive for a negative surface charge (downward polarized) film. We modeled these interactions with a constant-potential EDL model between dissimilar surfaces with the inclusion of a Stern layer. We report the surface potentials at the inner and outer-Helmholtz planes both for polarization states and for a range of ionic strength solutions. Effects of free-charge carriers, limitations of the analytical model, and effects of surface roughness are discussed.

Short TitleAcs Applied Materials & Interfaces