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Experimental Search for High Curie Temperature Piezoelectric Ceramics with Combinatorial Approaches Wei Hu Iowa State University

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Experimental Search for High Curie Temperature Piezoelectric Ceramics with Combinatorial Approaches Wei Hu Iowa State University Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2011 Experimental search for high Curie temperature piezoelectric ceramics with combinatorial approaches Wei Hu Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Materials Science and Engineering Commons Recommended Citation Hu, Wei, "Experimental search for high Curie temperature piezoelectric ceramics with combinatorial approaches" (2011). Graduate Theses and Dissertations. 10246. https://lib.dr.iastate.edu/etd/10246 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Experimental search for high Curie temperature piezoelectric ceramics with combinatorial approaches By Wei Hu A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Materials Science and Engineering Program of Study Committee: Xiaoli Tan, Co-major Professor Krishna Rajan, Co-major Professor Mufit Akinc, Hui Hu, Scott Beckman Iowa State University Ames, Iowa 2011 Copyright © Wei Hu, 2011. All rights reserved. ii Table of Contents Abstract .................................................................................................................................... iv 1. Introduction ........................................................................................................................... 1 References ............................................................................................................................. 4 2. Literature review ................................................................................................................... 5 2.1 Piezoelectric materials ..................................................................................................... 5 2.2 Ferroelectric materials and the Curie temperature .......................................................... 6 2.3 Ferroelectric crystals and the perovskite structure .......................................................... 8 2.4 Perovskite solid solution and the morphotropic phase boundary (MPB) ...................... 10 2.5 Curie temperature in solid solution of perovskites ........................................................ 13 2.6 Combinatorial processing .............................................................................................. 17 References ........................................................................................................................... 20 3. Experimental procedure ...................................................................................................... 23 3.1 Sample preparations ...................................................................................................... 23 3.2 Structure characterization .............................................................................................. 24 3.3 Electrical property measurements ................................................................................. 25 4. Combinatorial processing libraries for bulk BiFeO3–PbTiO3 piezoelectric ceramics ........ 26 4.1 Abstract ......................................................................................................................... 26 4.2 Introduction ................................................................................................................... 27 4.3 Experimental ................................................................................................................. 28 4.4 Results and discussion ................................................................................................... 31 4.5 Conclusions ................................................................................................................... 35 4.6 Acknowledgements ....................................................................................................... 36 References ........................................................................................................................... 37 5. BiFeO3–PbZrO3–PbTiO3 ternary system for high Curie temperature piezoceramics ........ 39 5.1 Abstract ......................................................................................................................... 39 5.2 Introduction ................................................................................................................... 40 5.3 Experimental ................................................................................................................. 41 5.4 Results and discussion ................................................................................................... 42 5.5 Conclusions ................................................................................................................... 55 5.6 Acknowledgement ......................................................................................................... 56 iii References ........................................................................................................................... 57 6. Piezoelectric ceramics with compositions at the morphotropic phase boundary in the BiFeO3–PbZrO3–PbTiO3 ternary system ................................................................................ 60 6.1 Abstract ......................................................................................................................... 60 6.2 Introduction ................................................................................................................... 61 6.3 Experimental procedure ................................................................................................ 62 6.4 Results ........................................................................................................................... 63 6.5 Discussion ..................................................................................................................... 74 6.6 Conclusions ................................................................................................................... 77 References ........................................................................................................................... 78 7. Experimental confirmation of high Curie temperature ferroelectric ceramics BiLuO3– PbTiO3 predicted by statistical modeling ............................................................................... 81 7.1 Introduction ................................................................................................................... 81 7.2 Experimental ................................................................................................................. 81 7.3 Results and discussion ................................................................................................... 82 7.4 Conclusions ................................................................................................................... 84 References ........................................................................................................................... 86 8. General conclusions and future work ................................................................................. 88 8.1 General conclusions ...................................................................................................... 88 8.2 Recommendations for future study ............................................................................... 92 References ........................................................................................................................... 93 Acknowledgement .................................................................................................................. 94 Appendix: publication list ....................................................................................................... 95 iv 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
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