|Title||Crystallization and grain growth characteristics of yttria-stabilized zirconia thin films grown by pulsed laser deposition|
|Publication Type||Journal Article|
|Year of Publication||2011|
|Authors||Heiroth, S, Frison, R, Rupp, JLM, Lippert, T, Meier, EJBarthaz, Gubler, EMueller, Doebeli, M, Conder, K, Wokaun, A, Gauckler, LJ|
|Journal||Solid State Ionics|
|Pagination||12 - 23|
Knowledge about the crystallization and grain growth characteristics of metal oxide thin films is essential for effective microstructural engineering by thermal post-annealing and the integration to Si-based miniaturized electroceramic devices. Finite size and interface effects may cause fundamentally different behavior compared to three dimensional macroscopic systems. This work presents a comprehensive investigation of the crystallization kinetics and microstructural evolution upon thermal post-annealing of amorphous 200 nm and 1.2 mu m thin films of 8 mol% yttria-stabilized zirconia grown by pulsed laser deposition (PLO) using ex- and in-situ X-ray diffraction, Raman spectroscopy, and electron microscopy techniques. The layers exhibit a remarkably low crystallization temperature of 200-250 degrees C while exposure to energetic electrons induces the formation of randomly dispersed -20 nm sized crystallites already at ambient temperature. The isothermal amorphous to crystalline phase transformation kinetics can be described quantitatively by the Johnson-Mehl-Avrami-Kolmogorov model. They reveal characteristics of a three dimensional growth under cation bulk diffusion control with heterogeneous nucleation that changes from continuous to instantaneous initial seeding at temperatures above 300 degrees C. Large (>100 nm) equiaxed grains are formed rapidly without a stabilization of transient nanocrystals during the thermally induced phase transformation. A stagnation of normal grain growth resulting in a logarithmic normal size distribution is observed once the average grain dimensions approach the film thickness. The results on the crystallization and grain growth of the PLD-grown YSZ films are evaluated with regards to the fabrication of YSZ solid electrolyte membranes for Si-supported micro solid oxide fuel cells and gas sensors. (C) 2011 Elsevier B.V. All rights reserved.