Electrical and Computer Engineering ETDs

Publication Date

5-2-1988

Abstract

A study of visible light scattering in thin plates of ceramic PLZT is presented. A scattering model is developed on the basis of multiple refraction from randomly oriented walls in a birefringent medium. The results of this model are compared to measurements of longitudinal-mode light scattering from thin (250 - 650µm) PLZT plates of three different ceramic compositions. The observed light scattering by these ceramics is attributed to two mechanisms which are linked to field-induced ferroelectric anisotropies. The first, referred to by this study as "uncorrelated birefringence," corresponds to the independently-random changes in the index ellipsoid known to occur at ceramic grain boundaries and at the walls of large (with respect to light wavelength) domains. The second scattering mechanism, referred to as "correlated birefringence," is thought to cause the light scattering in certain PLZT compositions which is characteristic of small, ordered, and birefringent structures. The physical origins of the second mechanism may be explained by fine, intra-grain, strain-relieving domain formations that were previously observed in PLZT by electron microscopy. Visible light scattering in PLZT ceramics is shown to be strongly influenced by photo-induced space charge, and arguments are presented which link light scattering and space charge effects to the ceramic grain size. Calculations of various domain-switching statistics for ferroelectric perovskite ceramics are presented. These statistics are shown to depend on the crystal symmetry of the unit cell, and therefore may be useful in optical characterizations of material phase. A review of the primary electrical, ferroelectric, and electrooptic properties of PLZT ceramics is also included.

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Victor W. Bolie

Second Committee Member

Carla Wofsy

Third Committee Member

Russell H. Seacat

Fourth Committee Member

John R. McNeil

Fifth Committee Member

Donald L. Kendall, Sixth Committee Member: Cecil Land

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