Structural Characterization of Sputtered Composite Stabilized ZrO₂ Thin Films

Abstract

Zirconia (ZrO2) exhibits three different polymorphic phases as a function of the thermal and pressure conditions (cubic, tetragonal and monoclinic). The use of zirconia coatings at high temperatures requires it to be stabilized at room temperature in order to maintain the high temperature phases when subjected to thermal cycles. For this purpose, this work reports different ways to stabilize ZrO2 coatings produced by DC reactive magnetron sputtering. We have produced stabilized ZrO2 coatings by doping with other metallic and rare earth oxides (Y2O3 and Gd2O3), depositing nanostructured ZrO2 crystallites in an amorphous Al2O3 matrix and using a ZrO2/Al2O3 nanolaminated structure. A comparative study of the coatings produced is presented along with their structural stabilization using different approaches. For the doped coatings the tetragonal or cubic phases were obtained as a function of the dopant percentage and for the nanostructured and nanolayered structures the stabilization mechanism is related to the constraining of the zirconia nanocrystallites and the capacity to maintain its size under certain value.