Theoretical Calculation of the Local Heating Effect on the Crystallization of TiO2 Prepared by Sparking Anodization

Sparks are frequently observed during dielectric breakdown on valve metal oxide films, and several papers investigated their correlation with the oxide crystallization. In this work, the effect of high temperature of a spark was studied using finite element method. An important result is that the oxide area heated above the oxide fusion temperature is more than 50 times larger than the diameter of the channel generated during the breakdown event, meaning that just a few numbers of sparks could lead to a large area of oxide crystallization. Besides, the heated area is proportional to the spark temperature and to the oxide thickness. Finally, using a factorial design, a cross effect was also detected between the channel temperature and the barrier oxide thickness.