Temperature- and electron-beam-induced crystallization of zirconia thin films deposited from an aqueous medium:: a transmission electron microscopy study

Thin zirconia films prepared by self-assembled monolayer-mediated deposition from an aqueous medium were investigated by transmission electron microscopy and electron-energy-loss spectroscopy. As-grown films were amorphous, and annealing at temperatures below 525degreesC did not influence the film structure. Annealing at 550degreesC led to crystallization; amorphous material transformed into the tetragonal phase of ZrO2 (t-ZrO2), yielding a polycrystalline film consisting of 10-50 nm sized grains. After annealing at 600degreesC, a small fraction of monoclinic phase was detected in addition to the tetragonal phase. Sulphur signals were visible in energy-dispersive X-ray spectra of as-grown and of annealed films, with a reduced sulphur content after annealing. Electron-beam irradiation also induced crystallization of amorphous material in as-grown films to give t-ZrO2; in this case the grains forming the polycrystalline film were only 5-10 nm in size.