Thin Solid Films, Vol.626, 17-24, 2017
Pt thin film transient mobility over yttria stabilized zirconia
Platinum thin films cover supports like yttria stabilized zirconia, titanium dioxide and graphite as a precursor to create catalysts and electrodes with micro-and nanostructures that improve their reactivity. Due to the difference of free energy per area between a thin film and agglomerated particles, Pt migrates when annealed above 400 degrees C, thus forming three-phase boundaries. Kinetic studies based on temperature demonstrated that holes form first. As the holes grow larger, bridges form between Pt domains and finally break leaving isolated islets. Here we report how Pt thin films (15 nm to 30 nm-thick) morphology evolves as a function of both temperature (550 degrees C to 1000 degrees C) and time (up to 16 h). Starting from a 30 nm-thick film, the support uncovered area and islet diameter reach respectively a maximum and a minimum at 12 h when annealed at 700 degrees C. We show that beyond this time islets are coarsening, the platinum reforms bridges, the uncovered area and the particle height decrease, The transition time is only 4 h for 15 nm and 700 degrees C and it is less than 8 h for 30 nm and 1000 degrees C. (C) 2017 Elsevier B.V. All rights reserved.