Zirconia-metal (Al, Y, Ti) oxide nanolaminate films

Our work on ZrO2 when this oxide is combined with other metal oxides in multilayer nanolaminate films is reviewed in this invited paper. ZrO2–Al2O3, ZrO2–Y2O3, and ZrO2–TiO2 nanolaminates were studied. The films were grown by sequential sputter deposition of individual oxide layers from metal targets using radio-frequency-excited, O2-bearing discharges. As the thickness of individual layers decreases, interfaces play an increasingly important role in determining the nanolaminatesʹ overall properties. These nanolaminates have different thermodynamic driving forces for interfacial cation mixing and interfacial atomic registry (heteroepitaxy or pseudomorphism). Three examples illustrate how strongly ZrO2 growth is influenced by its partner metal oxide through different interfacial reactions. These examples are superplastic tetragonal ZrO2 formation in ZrO2–Al2O3 films, cubic (Zr,Y)-oxide formation in ZrO2–Y2O3 films, and monoclinic (Zr,Ti)O2 formation (occurring in nature only at high pressure) in ZrO2–TiO2 films.