Fabrication of dense ionic and electronic conducting ceramics with enhanced oxygen ion permeation

(Stagg-Williams, Wu, and Nordheden)

One research focus in the laboratory of Dr. Stagg-Williams is exploring novel surface modification strategies to enhance the oxygen ion permeation through dense mixed (ionic and electronic) conducting ceramics (MIEC's). Over the past two decades, research into the use of dense membranes selective to oxygen permeation, has experienced significant growth. The potential applications, depending on the materials used, include solid oxide fuel cells, fuel processors, oxygen sensors, environmental remediation, oxygen pumps for medical applications, and oxygen generation systems. Recently, through an SGER funded project, Dr. Stagg-Williams has demonstrated that the addition of Pt metal to the source (air side) surface of a MIEC membrane can result in increased oxygen flux. In that work, Pt was added as 2-5 micron discs on the surface of a SrFeCo0.5O3.25-x membrane using photolithography and electron beam evaporation. The result was a doubling of the measured oxygen flux at temperatures between 600°C and 800°C and a decrease in the temperature required for the onset of oxygen ion permeation (Figure 1).

This collaborative project between Dr. Wu in the Physics Department and Dr. Stagg- Williams and Dr. Karen Nordheden in the Chemical and Petroleum Engineering Department further investigates the fabrication of novel MIEC membranes with enhanced ion oxygen permeation. Specifically, the role of the surface modification, the mechanism of oxygen ion formation and transport, the ability to disperse nanoparticles of Ag in the ceramic membrane and the role of the Ag in enhancing stability and permeation, and the deposition of the MIEC thin films onto robust porous substrates are all examples of the areas currently being investigated. The understanding of nanotechnology in these research projects is vital because of the need to obtain fundamental information about the interaction of each component in the MIEC ceramic material, the influence of crystal structure and the presence of defects on the oxygen ion flux, and the precise control of the pore size and structure to allow for defect free thin film deposition without creating mass transfer limitations in the nanoscale pores. The collaboration between physics and engineering allows for exploring novel fabrication techniques to increase oxygen ion permeation while studying ways to reducing the fabrication cost and engineer devices for potential applications. Projects for undergraduate students would combine fabrication and characterization studies to investigate one of the various aspects of the membrane modifications discussed above.