Soutenance de thèse – RAÚL PECH PISTÉ – Jeudi 19 mars à 17:00 (GMT+1) – Centro de Investigación Científica de Yucatán (CICY), Mérida – Mexico

 

The examination committee is composed of:

 

 

 

Solid dielectrics are critical components in high-power electronic applications. Under high voltage, these materials may experience dielectric breakdown, leading to catastrophic failure. This work investigates the dielectric breakdown behavior of epoxy and alumina as model systems to advance the understanding of the mechanisms governing this phenomenon. The study focuses on the role of defects and their contribution to dielectric failure. To evaluate the effect of conductive defects, epoxy was modified with graphenic sheets of varying lateral dimensions at concentrations below the percolation threshold. The results reveal that dielectric breakdown is strongly influenced by inclusion size. To assess the impact of natural defects, dedicated experiments were performed to characterize defect size in both epoxy and alumina. Electrical and mechanical properties were measured and used as inputs for existing analytical models. While conventional models tend to overestimate breakdown strength, predictive accuracy improves when electrical properties, fracture mechanics parameters, and defect morphology are incorporated. Finite element simulations further demonstrate that larger inclusions generate higher local electric field gradients, explaining the observed reduction in dielectric strength. Overall, the findings support an electro-fracture framework that accounts for local electric field intensification near defects as a robust approach to understanding dielectric breakdown.