Browsing by Author "Kopczyk, Michael"

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Low temperature sintering of Ba(Zr0.8‑xCexY0.2)O3-δ using lithium fluoride additive
(2010) Tsai, Chih-Long; Kopczyk, Michael; Smith, R. J.; Schmidt, V. Hugo
Lithium fluoride (LiF) was selected as a liquid phase sintering additive to lower the sintering temperature. The effects of LiF on the sinterability, microstructure, and electrochemical properties of Ba(Zr0.8 − xCexY0.2)O3 − δ (0 ≤ x ≤ 0.4) (BZCYs) ceramics were investigated. Using LiF as an additive, high density BZCYs ceramics can be obtained at sintering temperatures 200–300 °C lower than the usual 1700 °C with much shorter soaking time. Nuclear reaction investigations showed no lithium and a small amount of fluorine reside in the sample which indicates the non-concomitant evaporation of lithium and fluorine during the sintering process. Scanning electron microscopic investigations showed the bimodal structure of BZCYs ceramics and grain growth as Ce content increases. In a water saturated hydrogen containing atmosphere, BZCYs ceramics have higher conductivity when LiF is used in the sintering process. LiF-added BZCYs electrolyte-supported fuel cells with platinum electrodes were tested at temperatures from 500 to 850 °C. Results show that LiF is an excellent sintering additive for lowering the sintering temperature of BZCYs.
The structure of low-coverage Ti and V on the Al(001) crystal surface
(Montana State University - Bozeman, College of Letters & Science, 2010) Kopczyk, Michael; Chairperson, Graduate Committee: Richard J. Smith
The BFS (Bozzolo-Ferrante-Smith) Method for Alloys predicts that V and Ti would be effective interlayers to act as a diffusion barrier between a metal substrate and metal overlayer. Previous work from our group using the RBS channeling technique, determined that Ti is an effective interlayer between Fe and the Al(001) bulk substrate. The Fe-V-Al(001) system was not treated in this earlier work. This thesis is focused on studying the structure of the first bi-metal interface of these tri-metal systems, i.e. the Ti-Al(001) and V-Al(001) interfaces. LEIS (low-energy ion scattering spectroscopy) and LEED (low-energy electron diffraction) were used as experimental techniques specifically designed to study the surface structure of the top few layers of sample surfaces. LEED images for the Ti-Al case gave a c(2 x 2) pattern, a change from the standard p(1x1) pattern of the clean Al(001) surface, suggesting Ti occupies every other Al lattice site. LEIS results suggest that Ti prefers subsurface occupancy for sub-monolayer Ti coverage, and fills the surface layer as deposition thickness increases above but near 1 ML. LEED images for the V-Al system produced nothing out of the ordinary, but rather display a blurry p(1x1) image, becoming less distinct as V deposition thickness increases, suggesting that V atoms place themselves in the Al substrate with no specific order. LEIS results suggest that V prefers sub-surface occupancy for both sub-monolayer and higher (up to 2.5 ML) V coverage. Contrasting the results of these experiments, we determined that the structural characteristics of the V-Al interface differed enough from those of the Ti-Al interface, to conclude that V cannot be considered as effective of an interlayer as Ti.