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Chemical Expansivity in Ceramic Oxygen Transport Materials CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS by ANDREW CAI Submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Materials Science and Engineering CASE WESTERN RESERVE UNIVERSITY August, 2020 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis of Andrew Cai Candidate for the degree of Master of Science*. Committee Chair Professor Mark R. De Guire Committee Member Professor Alp Sehirlioglu Committee Member Professor K. Peter D. Lagerlöf Committee Member Doctor Hoda Amani Hamedani Date of Defense July 2, 2020 *We also certify that written approval has been obtained for any proprietary material contained therein. ACKNOWLEDGEMENTS I would like to thank my advisor, Professor Mark R. De Guire for his professional guidance and assistance. I would like to also thank the American Chemical Society Petroleum Research Fund for funding this project, as well as Doctor Ajit Sane of Volt Research LLC for extensive guidance on experimental work and OTM applications. Furthermore, I would like to thank my project co-workers from Case Western Reserve University, John Bradley, Sipei Li, and Mirko Antloga. I would like to personally thank Doctor John Gibbons, Chenxin Deng, and Doctor Benjamin Palmer from Case Western Reserve University, Sergio Medina from the Edward Orton Jr Ceramic Foundation, Eileen De Guire from the American Ceramic Society for their additional assistance. Moreover, I would like to thank Doctor Hisao Yamada, Cerone Inc., for donating several pieces of ceramic processing equipment that were invaluable to the materials synthesis aspects of this project. Finally, I would like to thank my respected committee members, Professor Alp Sehirlioglu, Professor K. Peter D. Lagerlöf, and Doctor Hoda Amani Hamedani. Table of Contents Table of Contents ............................................................................................................................ i List of Figures .................................................................................................................................. v List of Appendix Figures................................................................................................................ ix List of Tables ................................................................................................................................... x List of Appendix Tables ................................................................................................................. xii Abstract ............................................................................................................................................. xiii Chapter 1: Literature Review ......................................................................................................... 1 1.1. Introduction ................................................................................................................. 1 1.1.1. Technical background ............................................................................... 1 1.1.2. Project objectives ....................................................................................... 4 1.2. Literature review ......................................................................................................... 5 1.2.1. Perovskite oxides ....................................................................................... 5 1.2.2. Mixed electronic-ionic conducting oxygen transport membranes ..... 7 1.2.3. Lanthanum strontium ferrite-based membranes .................................. 9 1.2.4. Chemical expansion studies ..................................................................... 11 1.2.5. Dilatometric measurements of oxygen transport membranes ............ 12 Chapter 2: Experimental Procedures ........................................................................................... 14 2.1. Dilatometer calibration .............................................................................................. 14 2.1.1. Alumina reference sample calibration run ............................................. 14 2.1.2. Experimental runs on alumina reference sample deviation ................ 14 2.2. Purchased and synthesized powders for study ...................................................... 15 2.2.1. Compositions ............................................................................................. 15 2.2.2. Teraoka amorphous malic acid precursor method ............................... 16 i 2.3. Sample preparation .................................................................................................... 18 2.3.1. Pellet pressing............................................................................................. 18 2.3.2. Sintering ...................................................................................................... 19 2.4. Materials characterization: XRD, density, and SEM/EDS .................................. 19 2.5. Dilatometer operation and atmosphere control .................................................... 21 2.5.1. Gas setup .................................................................................................... 21 2.5.2. Oxygen step changes ................................................................................. 22 2.6. Data acquisition and reporting ................................................................................. 23 2.7. Calculations ................................................................................................................. 24 2.7.1. Chemical linear strain ................................................................................ 24 2.7.2. Coefficient of chemical expansion .......................................................... 25 Chapter 3: Results ........................................................................................................................... 26 3.1. Density ......................................................................................................................... 26 3.2. X-ray diffractometry ................................................................................................. 29 3.2.1. (La0.60Sr0.40)0.995 Co0.20Fe0.80O3-δ (FCM1) ................................ 30 3.2.2. (La0.80Sr0.20)0.95 FeO3-δ (FCM2) ................................. 31 3.2.3. (La0.20Sr0.80) Cr0.20Fe0.80O3-δ (PRAX1) ............................... 33 3.2.4. (La0.20Sr0.80) Co0.10 Cr0.20Fe0.70O3-δ (PRAX2) .............................. 34 3.2.5. (La0.50Sr0.50) Cr0.20Fe0.80O3-δ (CWRU1) ............................. 35 3.2.6. (La0.20Sr0.80) Co0.10 Cr0.10Fe0.80O3-δ (CWRU2) ............................. 37 3.2.7. (La0.20Sr0.80) Co0.10Cr0.10Mg0.05Fe0.75O3-δ (CWRU3) ............................. 38 3.2.8. (La0.50Sr0.50) Cr0.20Mg0.05Fe0.75O3-δ (CWRU4) ............................ 39 3.3. Scanning electron microscopy .................................................................................. 41 3.4. Energy dispersive x-ray spectroscopy ..................................................................... 50 ii 3.5. Linear strain versus oxygen step changes (800 °C, 900 °C, 1000 °C) ................ 53 3.5.1. (La0.60Sr0.40)0.995 Co0.20Fe0.80O3-δ (FCM1) ................................ 53 3.5.2. (La0.80Sr0.20)0.95 FeO3-δ (FCM2) ................................. 54 3.5.3. (La0.20Sr0.80) Cr0.20Fe0.80O3-δ (PRAX1) ............................... 54 3.5.4. (La0.20Sr0.80) Co0.10 Cr0.20Fe0.70O3-δ (PRAX2) .............................. 55 3.5.5. (La0.50Sr0.50) Cr0.20Fe0.80O3-δ (CWRU1) ............................. 55 3.5.6. (La0.20Sr0.80) Co0.10 Cr0.10Fe0.80O3-δ (CWRU2) ............................. 56 3.5.7. (La0.20Sr0.80) Co0.10Cr0.10Mg0.05Fe0.75O3-δ (CWRU3) ............................. 56 3.5.8. (La0.50Sr0.50) Cr0.20Mg0.05Fe0.75O3-δ (CWRU4) ............................ 57 3.6. Coefficient of chemical expansion ........................................................................... 58 3.7. Summary tables ........................................................................................................... 59 Chapter 4: Discussion of Results .................................................................................................. 63 4.1. Densification and sintering effects .......................................................................... 63 4.2. X-ray diffractometry .................................................................................................. 64 4.3. Scanning electron microscopy .................................................................................. 69 4.4. Energy dispersive x-ray spectroscopy ..................................................................... 70 4.5. Effect of pO2 and temperature on chemical linear strain ..................................... 71 4.6. Coefficient of chemical expansion ........................................................................... 79 4.7. Reproducibility ............................................................................................................ 79 Chapter 5: Conclusion .................................................................................................................... 81 Chapter 6: Future Work ................................................................................................................. 83 6.1. Scanning electron microscopy .................................................................................. 83 6.2. Elemental analysis .....................................................................................................
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