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Title:Phase development and texture for lead-based perovskite thin layers prepared by sol-gel processing
Author(s):Tani, Toshihiko
Doctoral Committee Chair(s):Payne, David A.
Department / Program:Engineering, Chemical
Engineering, Electronics and Electrical
Engineering, Materials Science
Discipline:Engineering, Chemical
Engineering, Electronics and Electrical
Engineering, Materials Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Chemical
Engineering, Electronics and Electrical
Engineering, Materials Science
Abstract:The evolution of phases and the development of texture were investigated for sol-gel derived lead-based perovskite thin layers. Dielectric and ferroelectric properties were examined in terms of crystal structure, microstructure, and preferred orientation. Ferroelectric La-modified Pb(Zr,Ti)O$\sb3$ (PLZT) and antiferroelectric PbZrO$\sb3$ (PZ) were chosen as materials which could be potentially used in integrated devices, including, sensors, actuators, and memory applications. Emphasis was placed on determining (i) the processing conditions necessary for the preparation of single-phase perovskite materials without the formation of undesired second phases, and (ii) factors which contribute to texture development in thin layers.
The computer controlled measurement system was designed to collect data as a function of frequency and temperature from many electroded locations. A microprobe positioner was equipped with computer-controlled three axis digital stepping motors so that it could probe multi-electroded dielectrics in a scan mode and collect statistically meaningful data.
Crystallization behavior of sol-gel derived PLZT was examined as a function of heat-treatment conditions, with and without an additional PbO layer on the top or bottom. The control of vapor pressure for lead-containing species in the local atmosphere during heat treatment was found to be important for the crystallization of the perovskite structure, and to prevent the formation of a non-ferroelectric phase.
Texture development was investigated for PLZT and PZ thin layers deposited on physically-deposited platinum electrodes with modified surface chemistries. The texture of the layers were found to be dependent on crystal structure and atomic constituents in the surface of the platinum, the lattice match between the host and the guest material, and the polymeric structure in the precursor solution and gel. In addition, epitaxial PLZT thin layers were prepared for the first time by sol-gel methods on platinized MgO single-crystal substrates.
Single-phase perovskite PZ thin layers were tailored with either a pseudocubic (111) or (100) orientation by the methods discovered in this research. The field-forced antiferroelectric (AFE)-to-ferroelectric (FE) phase transformation behavior was examined and thermal stability was investigated for the two orientations of PZ layers. (Abstract shortened by UMI.)
Issue Date:1994
Rights Information:Copyright 1994 Tani, Toshihiko
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9416441
OCLC Identifier:(UMI)AAI9416441

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