New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: I, Role of Oxidation State and Defect Concentration on Oxide Wettability by Gold

TLDR: In this article, a sessile drop setup was combined with an oxygen sensor, an electrochemical pump, and a renewable oxygen getter, which enabled the control of the defect concentration in the oxide and of the oxygen content in the metal.

Abstract: A sessile drop setup has been combined with an oxygen sensor, an electrochemical pump, and a renewable oxygen getter. The oxygen activity of a metal–oxide sample can be monitored in the 10−9–1 range, in a flowing gas, that enables the control of the defect concentration in the oxide and of the oxygen content in the metal. The stoichiometry of the substrate can also be modified by electrochemical reduction, allowing the oxygen activity of the sample to be monitored down to values as low as 10−20. The dependence on oxygen activity of the wetting and the thermodynamic adhesion of gold on sapphire, titanium oxides, and yttria-stabilized zirconia is presented to illustrate the versatility of the equipment.