Abstract Scope |
Yttria-Stabilized-Zirconia (YSZ) is used as a Thermal Barrier Coating (TBC) in turbine blades in its t' structure. Due to cation diffusion, t-YSZ transforms to yttrium lean tetragonal YSZ (t-YSZ) and yttrium rich cubic YSZ (c-YSZ). This process happens at a higher rate in the presence of water vapor in the system. In this work, we used first-principles Density Functional Theory (DFT) calculations to study the formation energy of cationic defects, V’’’’Zr and (V..OV’’’’Zr)’’ in YSZ at 1800 K, and how water species change those energetics. Our findings show that the formation energy of these defects is lower in c-YSZ in dry and wet conditions. Also, H+ reduces the formation energy of both defects in t-YSZ and c-YSZ structures, and its effect is more significant on (V..OV’’’’Zr)’’. |