Degree Type

Dissertation

Date of Award

2011

Degree Name

Doctor of Philosophy

Department

Materials Science and Engineering

First Advisor

Xiaoli Tan

Second Advisor

Krishna Rajan

Abstract

High temperature piezoelectric materials are needed for actuation and sensing applications in harsh environments such as engine health monitoring and space exploration. Ferroelectric ceramics are widely used in piezoelectric devices but their high temperature application is limited by the ferroelectric-to-nonferroelectric transition at the Curie temperature.

The BiFeO3-PbTiO3 (BF-PT) solid solution system is peculiar for its high Curie temperature and thus promising for high temperature piezoelectric applications. However, the high dielectric loss and high leakage current make it difficult to achieve good piezoelectric properties. In the present study, Pb(Mg1/3Nb2/3)O3 and PbZrO3 were used to modify BiFeO3-PbTiO3 to suppress the dielectric loss and enhance ferroelectric and piezoelectric properties. In order to study the interrelationship between compositions, processing conditions and electrical properties in a systematic and efficient way, combinatorial approaches were employed to generate composition variation and optimize processing conditions. A simple high throughput method for solid state synthesis of bulk piezoelectric ceramics has been realized by creating a one-dimensional temperature gradient in a horizontal tube furnace.

The doping of 2 mol.% Pb(Mg1/3Nb2/3)O3 was found effective in suppressing the dielectric loss while maintaining the high Curie temperature. Adding PbZrO3 to BiFeO3-PbTiO3 to form a ternary solid solution decreases the Curie temperature, enhances the room temperature dielectric permittivity, significantly suppresses the dielectric loss, considerably increases the remanent polarization, and improves the piezoelectric property. The good combination of Curie temperature and piezoelectric behaviors suggests that BiFeO3-PbZrO3-PbTiO3 ternary system is promising for high temperature piezoelectric application.

Synthesis and electrical measurement of the new binary system BiLuO3-PbTiO3, an example of experimental exploration guided by statistical modeling, is also presented. Addition of 10 mol. % BiLuO3 to PbTiO3 leads to a significant increase in the Curie temperature though the solubility is limited.

Copyright Owner

Wei Hu

Language

en

Date Available

2012-04-06

File Format

application/pdf

File Size

100 pages

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