Activation energy and grain growth in nanocrystalline Y-TZP ceramics

Grain growth of nanocrystalline yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) was studied between 1250 and 1650 °C and compared to the Y-TZP data from the literature. All the results exhibited two distinctly different behaviour, where slow and fast grain growth regimes with activation energies ∼280 and ∼546 kJ mol−1 prevail below and above ∼1400 °C, respectively. Analysis of the data with respect to the grain growth mechanisms and the diffusion kinetics was in agreement with limited Y3+ lattice diffusion within the cubic zirconia nano-grains below ∼1400 °C. This results in slow grain growth kinetics. Redistribution of Y3+ above ∼1400 °C together with the equilibrium phase assemblage lead to enhanced grain boundary diffusion of Y3+ and results in enhanced grain growth of the sub-micrometer tetragonal grains.