Effect of annealing on grain growth and Y segregation behavior in tetragonal ZrO2 thin film

In order to fabricate tetragonal yttria stabilized zirconia samples with large grain size, 3 mol% Y2O3 doped zirconia thin films were grown on (0001) alpha-Al2O3 substrate by pulsed laser deposition (PLD) followed by subsequent high temperature annealing. The thin film samples were annealed at 1200 degrees C, 1250 degrees C, 1300 degrees C, and 1350 degrees C in order to obtain larger grain size without Y segregation. The microstructure and chemical composition of these annealed films were analyzed using atomic force microscopy, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The as-grown thin film was found to be composed of [111]-oriented grains of similar to 100 nm connected with small-angle tilt boundaries. Based on analysis of annealed thin films, it was revealed that grain growth of tetragonal zirconia occurred anisotropically. Cross section scanning transmission electron microscopy observations revealed that such grain growth behavior is affected by the step-terrace structures of the sapphire substrate. Energy-dispersive X-ray spectroscopy showed that Y was found to distribute almost uniformly below 1300 degrees C but to segregate at the grain boundaries at 1350 degrees C. As a conclusion, the 1300 degrees C-annealed sample shows the largest grain size with homogeneous Y distributions.

Automated summary

Tetragonal yttria stabilized zirconia samples with large grain size were fabricated by pulsed laser deposition and high temperature annealing. The anisotropic grain growth of tetragonal zirconia was observed, influenced by the substrate structures. The 1300 degrees C-annealed sample showed the largest grain size with homogeneous Y distributions.