Phase transformation and nanocrystallite growth behavior of 2 mol% yttria-partially stabilized zirconia (2Y-PSZ) powders

Abstract Two mol% yttria-partially stabilized zirconia (2Y-PSZ) precursor powders were obtained through a co-precipitation process using ZrOCl 2 .8H 2 O and Y(NO 3 ) 3 .6H 2 O as starting materials. Phase transformation and crystallite growth behavior have been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). XRD results show that the crystal structure to be composed of coexisting tetragonal ZrO 2 (t-ZrO 2 ) and monoclinic ZrO 2 (m-ZrO 2 ) when the 2Y-PSZ freeze dried precursor powders was calcined at 773–1273 K for 2 h. The fraction of m-ZrO 2 content is lower than 3.0 % when the calcination temperature is lower than 1073 K, whereas m-ZrO 2 content rapidly increases to 8.7 % with the increase of calcination temperature to 1273 K. The crystallite size of t-ZrO 2 increases from 12.3 to 30.2 nm when calcination temperature increased from 773 to 1273 K. In addition, the activation energy of t-ZrO 2 and m-ZrO 2 crytallite growth in 2Y-PSZ freeze dried precursor powders are 29.2 and 21.8 kJ/mol, respectively.