Alex P. Cocco

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.

Analysis of Solid Oxide Fuel Cell LSM-YSZ Composite Cathodes With Varying Starting Powder Sizes

Solid oxide fuel cell cathodes have been examined using non-destructive x-ray nanotomography. The cathodes examined were a composite of strontium-doped lanthanum manganite (LSM) and yttria-stabilized zirconia (YSZ), with three different starting powder sizes of 0.3 μm, 0.5 μm, and 1 μm. Differential absorption contrast imaging was performed over the manganese K-edge (6539 eV) for the identification of the LSM, YSZ, and pore phases. The three phases were each segmented from reconstruction of the tomography data. Three dimensional volumes of the segmented phases were used to calculate structural characterization parameters of the sample including porosity, pore size distributions, and mean phase sizes. These parameters are reported and some correlations are drawn to the starting powder size.Copyright