Issues in Grain Boundary Transport: Role of Boundary Chemistry and Structure

For many technological applications of ceramic components, the nature of the transport kinetics is critical to their functionality and reliability. Examples include oxide scales on high temperature alloys, and solid oxide fuel cells. For most crystalline ceramic systems, diffusion along grain (or interphase) boundaries is the rate-controlling transport mechanism. However, the overall complexity of general boundaries in ceramics has stymied deeper understanding. For example, characteristics such as the boundary structure, bonding, concentration and location of segregant ions, are most-likely inter-dependent, with different functional dependences on temperature. Additional complications include considerations of crystal defects and space charge, factors which differ from system to system. Perhaps not surprisingly, therefore, on the atomic level, the influences of boundary structure and chemistry on diffusional transport are currently not well understood. For example, although it has been shown that foreign ions can slow transport along boundaries, the process by which this occurs is not clear. Further, greater insight is needed into the mechanistic significance of commonly measured experimental quantities, such as the activation energy.

The aim of this conference is to extend the boundaries of fundamental understanding in the topic area, by bringing together eminent researchers and students in the field. Talks will cover both oxide and non-oxide ceramics, and address modeling of boundaries and boundary transport, state-of-the-art experimental techniques for characterizing boundary structures, and measurements of transport properties. By disseminating new insights into both theoretical and experimental aspects of this topic, it is hoped to further understanding, and evaluate the prospects for material interfaces with designer transport properties.