Matthew B. DeGostin

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions.

Characterization of Solid Oxide Fuel Cell Materials Based on Microstructural Skeletonization

The understanding of the relationship between the microstructure of materials for energy applications and their transport and electrochemical properties is needed to optimize their long-term performance. The improvements of 3D imaging techniques such as x-ray nanotomography allow access to geometrical and elemental information with ever increasing accuracy and details. These advances warrant determining new relevant metrics for material characterization, the calculation of which will require adaptations of the methodologies for parameter extraction.This study presents the development of a tool for the characterization of porous, heterogenous materials that provides coherent geometrical and topological information. We illustrate the relevance of the methodology by discussing the differences between geometrical concepts for estimating phase size distributions of real heterogeneous materials investigated using x-ray nanotomography and how research between different scales and physics can be bridged. This is achieved by providing, on the one hand, inputs to classical continuum models and, on the other hand, by synergetic combination with discrete element methods.Copyright