Field-Induced Phase Transformations in Relaxor Ferroelectric Single Crystals

203 Pages·2014·6.03 MB·English

UCLA
UCLA Electronic Theses and Dissertations
Title
Field-Induced Phase Transformations in Relaxor Ferroelectric Single Crystals
Permalink
https://escholarship.org/uc/item/49m7w7cw
Author
Gallagher, John Alfred
Publication Date
2014

Peer reviewed|Thesis/dissertation
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University of California
UNIVERSITY OF CALIFORNIA
Los Angeles

Field-Induced Phase Transformations in Relaxor Ferroelectric Single Crystals

A dissertation submitted in partial satisfaction of the
requirements for the degree Doctor of Philosophy
in Mechanical Engineering

by

John Alfred Gallagher

2014
© Copyright by
John Alfred Gallagher
2014
ABSTRACT OF THE DISSERTATION

Field-Induced Phase Transformations in Relaxor Ferroelectric Single Crystals

By

John Alfred Gallagher
Doctor of Philosophy in Mechanical Engineering
University of California, Los Angeles, 2014
Professor Christopher S. Lynch, Chair

The goal of this dissertation is to develop a better understanding of the large field
behavior and field induced phase transformations in relaxor ferroelectric single crystals.
Development of relaxor ferroelectric single crystals requires experimental characterization of the
thermo-electro-mechanical behavior to determine the linear coefficients as a function of stress,
electric field, and temperature, and the limitations on linear behavior imposed by field driven
phase transformations. The characterization of the large field behavior including dielectric loss,
material coefficients, non-linear field induced phase transformations, and the mechanical,
electrical, and thermal thresholds for linear behavior are discussed in detail. The full
characterization of many compositions of [001]C and [011]C cut and poled single crystal lead
indium niobate – lead magnesium niobate – lead titanate, xPb(In1/2Nb1/2)O3-(1-x-
y)Pb(Mg1/3Nb2/3)O3-yPbTiO3 (PIN-PMN-PT), is presented and the effect of composition on the
field induced phase transformation is discussed. PIN-PMN-PT with low PT concentrations was
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found to have a distributed phase transformation over a range of applied fields while PIN-PMN-
PT with higher PT concentrations had discontinuous phase transformation behavior. Increasing
the PT concentration or decreasing the PIN concentration increased the material coefficients but
decreased the transformation threshold. A new approach to characterizing the large field
behavior of relaxor ferroelectric single crystals was developed based on a combination of a
work-energy based model of the driving forces for the phase transformation together with
electric field loading while monitoring strain and electric displacement, and a measurement of
mechanical compliance. The model was verified using the results from experimental
characterization of PIN-PMN-PT and was found to accurately simulate the phase transformation
behavior under combined mechanical, electrical, and thermal loads.

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The dissertation of John Alfred Gallagher is approved.
Gregory P. Carman
Nasr Ghoniem
Ertugrul Taciroglu
Christopher S. Lynch, Committee Chair

University of California, Los Angeles
2014

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For my beloved wife,
Stephanie
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TABLE OF CONTENTS

ABSTRACT................................................................................................................................... ii
TABLE OF CONTENTS............................................................................................................. vi
LIST OF FIGURES....................................................................................................................... x
LIST OF TABLES...................................................................................................................... xxi
LIST OF SYMBOLS................................................................................................................ xxiii
ACKNOWLEDGEMENTS................................................................................................... xxviii
VITA.......................................................................................................................................... xxix
CHAPTER 1: INTRODUCTION................................................................................................. 1
1.1. Motivation......................................................................................................................... 1
1.2. Contents of the Dissertation............................................................................................. 3
CHAPTER 2: BACKGROUND................................................................................................... 6
2.1. History of Piezoelectrics and their Applications............................................................ 6
2.2. Ferroelectrics.................................................................................................................... 8
2.2.1. Perovskite Structure................................................................................................. 8
2.2.2. Multiscale Governing Behavior............................................................................. 11
2.2.3. Thermodynamics and Devonshire Theory............................................................. 14
2.2.4. Relaxor Ferroelectrics........................................................................................... 19
2.2.5. Phase Transformations.......................................................................................... 20
CHAPTER 3: LARGE FIELD DIELECTRIC LOSS IN FERROELECTRIC
MATERIALS............................................................................................................................... 30
3.1. Introduction.....................................................................................................................30
vi
3.2. Large Field Dielectric Loss Model................................................................................ 33
3.3. Effect of Field Driven Phase Transformation on the Loss Tangent of PMN-0.32PT
Single Crystals................................................................................................................. 37
3.3.1. Experimental Approach......................................................................................... 39
3.3.2. Experimental Results............................................................................................. 41
3.3.3. Analysis and Discussion........................................................................................ 42
3.3.4. Concluding Remarks.............................................................................................. 45
3.4. Large Field Dielectric Loss in Relaxor Ferroelectric PLZT....................................... 46
3.4.1. Experimental Approach......................................................................................... 49
3.4.2. Experimental Results............................................................................................. 51
3.4.3. Analysis and Discussion........................................................................................ 56
3.4.4. Concluding Remarks.............................................................................................. 60
3.5. Stress and Electric Field Gradient Contributions to Dielectric Loss with
Interdigitated Electrodes................................................................................................ 60
3.5.1. Experimental Approach......................................................................................... 62
3.5.2. Experimental Results............................................................................................. 64
3.5.3. Analysis and Discussion........................................................................................ 67
3.5.4. Concluding Remarks.............................................................................................. 73
CHAPTER 4: COMPOSITIONAL DEPENDENCE OF FIELD INDUCED PHASE
TRANSFORMATIONS IN [011]C PIN-PMN-PT RELAXOR FERROELECTRIC SINGLE
CRYSTALS WITH d32 PIEZOELECTRIC MODE................................................................ 74
4.1. Introduction.....................................................................................................................75
4.2. Experimental Approach................................................................................................. 79
vii
4.2.1. Specimen Preparation............................................................................................ 79
4.2.2. Experimental Arrangement.................................................................................... 80
4.3. Results.............................................................................................................................. 83
4.4. Analysis and Discussion................................................................................................. 97
4.5. Concluding Remarks.................................................................................................... 103
CHAPTER 5: COMPOSITIONAL DEPENDENCE OF ELECTRO-MECHANICAL
PROPERTIES AND FIELD INDUCED PHASE TRANSFORMATIONS IN [001]C PIN-
PMN-PT SINGLE CRYSTALS............................................................................................... 105
5.1. Introduction...................................................................................................................106
5.2. Experimental Approach............................................................................................... 109
5.2.1. Specimen Preparation.......................................................................................... 109
5.2.2. Experimental Arrangement.................................................................................. 110
5.3. Experimental Results.................................................................................................... 112
5.4. Analysis and Discussion...............................................................................................120
5.5. Concluding Remarks.................................................................................................... 124
CHAPTER 6: COMBINING EXPERIMENTS AND MODELING TO CHARACTERIZE
FIELD DRIVEN PHASE TRANSFORMATION IN RELAXOR FERROELECTRIC
SINGLE CRYSTALS................................................................................................................ 126
6.1. Introduction................................................................................................................. 127
6.2. Model Methodology.................................................................................................... 132
6.3. Results.......................................................................................................................... 142
6.3.1. Partial Phase Transformation Model................................................................. 142
6.3.2. Full Transformation Model................................................................................. 144
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