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iDEA: DREXEL LIBRARIES E-REPOSITORY AND ARCHIVES

iDEA: DREXEL LIBRARIES E-REPOSITORY AND ARCHIVES

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Processing of Pb(Mg1/3Nb2/3)O3-PbTiO3 by a novel coating approach

Details
Title
Processing of Pb(Mg1/3Nb2/3)O3-PbTiO3 by a novel coating approach
Author(s)
Gu, Huiming
Advisor(s)
Shih, Wei-Heng; Shih, Wan Y.
Keywords
Materials engineering; Ferroelectric crystals; Coatings
Date
2003-11
Publisher
Drexel University
Thesis
Ph.D., Materials Engineering -- Drexel University, 2003
Abstract
Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is an important ferroelectric material that has outstanding room temperature dielectric constant and electro-mechanical coefficient. Unlike most other ferroelectric materials, PMN-PT is difficult to prepare because of the formation of unwanted pyrochlore phase. Many methods of PMN-PT preparation have been developed to overcome this problem over the past decades. The remaining major problems for these methods are the high sintering temperature of 1200°C and the complex processing steps. In this thesis, a new coating method is introduced for PMN-PT processing. This method involves coating Mg(OH)2 on the surface of Nb2O5 particles to increase the mixing of chemical components and enhance the complete transformation from pyrochlore phase to perovskite phase. With this method, the processing is simplified to only one-step calcination for PMN-PT powder preparation and one-step sintering for PMN-PT dense part preparation. At the same time, the sintering temperature is decreased to 1000°C. To gain fundamental understanding on the colloidal coating process, a modified SAK simulation model was developed. In powder processing, it was shown that smaller particle size and better powder configurations were the reasons for eliminating pyrochlore phase. On the other hand, smaller particle size and reactive sintering are responsible for the lower temperature sintering. Finally, processing optimization study showed that 0-2 at.% PbO excess is the ideal composition for high quality PMN-PT preparation.
URI
http://hdl.handle.net/1860/252
In Collections
Theses, Dissertations, and Projects

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