High-temperature phase in zirconia film fabricated by aerosol gas deposition and its change upon subsequent heat treatment

Abstract

A zirconia film synthesized by aerosol gas deposition (AGD) contains a high-temperature phase of zirconia even if synthesized at room temperature. We attempted to clarify the change of the high-temperature phase upon subsequent heat treatment using zirconia powder with a mean particle diameter of 7.7 µm obtained by the dry method. X-ray diffraction (XRD) analysis was used to examine the crystal structure evolution of the AGD zirconia film during heat treatment, and a high-temperature XRD system was also used to measure crystal size at various heating temperatures. The as-deposited zirconia AGD film was found to be composed of monoclinic crystallites about 10 nm in diameter and tetragonal crystallites about 6 nm in diameter. The tetragonal crystallites were stable up to 1373 K, increasing their diameters to 14 nm upon heating. Then, the internal stress of the AGD zirconia film as well as the effects of heating temperature and holding time on internal stress were evaluated. The internal stress induced in the zirconia AGD film was 1.7 GPa, which decreased only up to 1.4 GPa after heat treatment at 1473 K.