The effects of large AC electric fields on the properties of ferroelectric lead zirconate titanate thin films
Abstract
The initial motivation of the research presented here was to understand some novel phenomena reported in compositionally graded ferroelectric films. The phenomenon of primary interest was the translation of ferroelectric hysteresis loops along what is normally regarded as the polarization axis, which was interpreted as a polarization offset with anamolously large and unphysical values. The fabrication of compositionally graded Pb(Zr,Ti)O 3 (PZT) thin films is presented along with the observation of hysteresis loop translations. These hysteresis loop translations were found to be due to a dc voltage offset which develops on the sample capacitor. In addition, these voltage offsets were found to be sensitive to the oxygen partial pressure of the atmosphere in which the films were situated. Similar oxygen dependent voltage offsets were observed for non-graded PZT films. It is proposed that the observed voltage offsets are ultimately the result of a redistribution of oxygen vacancies at the film surface. This hypothesis is supported by the observation of oxygen dependent voltage offsets in yttria stabilized zirconia films. Two models are proposed which attempt to explain how a redistribution of oxygen vacancies might result in the observed voltage offsets. These models are presented along with experimental results which offer insights into their validity. Finally, a course for future studies is recommended.
Degree
Ph.D.
Advisors
Mansour, Purdue University.
Subject Area
Condensation
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.