Ph.D. Proposal Presentation by William S. Oates
Wednesday, September 17, 2003

(Dr. Chris Lynch, advisor)

"Fracture of Ferroelectric Material"

Abstract

The number of commercially available devices that utilize ferroelectric materials has dramatically increased over the past decade. Large electro-mechanical loading at high frequency is often required to compete with conventional high power applications which has impeded the progress of macro-scale device implementation due to a lack of understanding the material’s failure mechanisms.

The focus of the proposed research is to gain additional insight into mechanisms causing failure in ferroelectric materials and devices. Preliminary theoretical work has provided solutions to the anisotropic linear elastic crack problem using the generalized Stroh formalism and a new orthotropic rescaling technique. Subcritical crack growth has been characterized on PZT (Pb0.99[Zr0.45Ti0.47(Ni0.33Sb0.66)0.08]O3) using compact tension specimens. Electrical boundary conditions and relative humidity conditions affected crack growth.

The preliminary work has motivated additional theoretical and experimental investigations. An energy based model is under investigation to add insight into how electro-mechanical loading drives crack propagation. The additional experimental work will include comparing the fracture behavior of relaxor based ferroelectric single crystal PZN-PT to a different composition of ceramic PZT.