Crystallization kinetics and growth mechanism of 8 mol percent yttria-stabilized zirconia (8YSZ) nano-powders prepared by a sol-gel process

摘要

Eight mol percent yttria-stabilized zirconia (8YSZ) gel powders were synthesized at 348 K for 2h using ZrOCl_2 centre dot 8H_2O and Y(NO_3)_3 centre dot 6H_2O as starting materials in an ethanol-water solution by a sol-gel process. The crystallization kinetics and growth mechanism of the 8YSZ gel powders have been investigated using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The XRD results and SAED pattern show that the 8YSZ gel powders calcined at 773 K for 2 h is a cubic ZrO_2. The activation energy for the crystallization of the cubic ZrO_2 formation in the 8YSZ gel powders is determined as 231.76 kJ/mol by a non-isothermal DTA method. Both growth morphology parameter (n) and crystallization mechanism index (m) are close to 3.0 indicating that the bulk nucleation is dominant in the cubic ZrO_2 formation. The TEM examination shows that the cubic ZrO_2 has a spherical-like morphology with a size ranging from 10 to 20 nm.