Browsing by Author "Song, K."
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- ItemCerium reduction at the interface between ceria and yttria-stabilised zirconia and implications for interfacial oxygen non-stoichiometry(New York, NY : American Inst. of Physics, 2014) Song, K.; Schmid, H.; Srot, V.; Gilardi, E.; Gregori, G.; Du, K.; Maier, J.; Van Aken, P.A.Epitaxial CeO2 films with different thickness were grown on Y2O3 stabilised Zirconia substrates. Reduction of cerium ions at the interface between CeO2 films and yttria stabilised zirconia substrates is demonstrated using aberration-corrected scanning transmission electron microscopy combined with electron energy-loss spectroscopy. It is revealed that most of the Ce ions were reduced from Ce 4+ to Ce3+ at the interface region with a decay of several nanometers. Several possibilities of charge compensations are discussed. Irrespective of the details, such local non-stoichiometries are crucial not only for understanding charge transport in such hetero-structures but also for understanding ceria catalytic properties.
- ItemGlass-forming ability, phase formation and mechanical properties of glass-forming Cu-Hf-Zr alloys(Amsterdam : Elsevier B.V., 2019) Kosiba, K.; Song, K.; Kühn, U.; Wang, G.; Pauly, S.The influence of Hf additions on the glass-forming ability (GFA), phase formation and mechanical properties of Cu50HfxZr50-x (x = 2,5,10,20 at.%) alloys has been systematically investigated. We report on a distinct correlation between phase formation and GFA of Cu50Zr50-based alloys. Increasing additions of Hf reduce the thermal stability of the high-temperature B2 Cu(Hf,Zr) phase, while the thermal stability of the corresponding undercooled melt is enhanced. The GFA of these alloy series gradually raises up to 10 at.% Hf, whereas at 20 at.%Hf, the GFA is drastically lowered, since the B2 Cu(Hf,Zr) phase becomes unstable and the precipitation of the low-temperature equilibrium phases is favoured. This interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass composites. These composites not only show appreciable macroscopic plastic strain, but also high yield strength.