Accommodation and Stability of Alloying Elements in Amorphous Grain Boundaries of Zirconia

A combination of modeling methods has been used to analyze the configurational entropy of undoped and doped amorphous and crystalline ZrO2 systems. In this work, chromia, Cr2O3, has been analyzed as a dopant in crystalline and amorphous zirconia currently at 10 at.% chromium and at a range of temperatures between 300 and 2,000 K. These systems have been modeled using a range of techniques, including molecular dynamics and density functional theory. Modifications to the structures upon introducing chromium is observed. For the first time, the entropy of the amorphous system is modeled and compared to the crystalline system. Amorphous undoped systems have higher configurational entropies owing to greater disorder observed compared with the crystalline counterpart. Dopants act to modify the original crystalline lattice, inducing greater disorder compared with the amorphous counterpart. Further work will analyze whether this difference in entropy has an impact on the overall Gibbs free energy and stabilization of amorphous chromium-doped ZrO2 systems.