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Thermal and structural studies of sol–gel derived yttria-doped ZrO2 nanoparticles: effect of annealing condition

Sol-gel derived zirconia, ZrO2 (stabilized by yttria in 5 mol %) nanocrystals (5YSZ) were annealed at different temperatures in different atmosphere conditions (air and vacuum) and investigated. Prepared samples were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier- transform infrared spectroscopy (FT-IR) and micro-Raman spectroscopy. The results of DTA and XRD analysis show the zirconia crystallization onset at temperature no lower than 400 ºC. Average crystallite size of the 5YSZ annealed in air at 400, 600, 700 and 800 °C were calculated to be 10, 15, 22 and 33 nm, respectively. On the other hand, crystallite size remains in the range 4–13 nm when the heat treatment was conducted in vacuum. Annealing atmosphere affects crystallization, resulting in lower thermal treatment requirements and enabling controlled crystallite growth. XRD and micro-Raman spectroscopy showed nanocrystalline 5YSZ samples were successfully stabilized in the tetragonal phase and preserved phase stability over the investigated thermal treatment range.

zirconia; yttria doping; sol-gel; annealing

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