Topological Phases, Boson mode, Immiscibility window and Structural Groupings in Ba-Borate and Ba-Borosilicate glasses A dissertation submitted to Division of Research and Advanced Studies University of Cincinnati In partial fulfillment of the requirements for the degree of Doctor of Philosophy (Ph.D.) In the Department of Electrical Engineering and Computing Systems Of the College of Engineering and Applied Sciences October 2015 by Chad Holbrook M.S., University of Cincinnati, 2007 B.S., Northern Kentucky University, 2003 Committee Chair: Punit Boolchand, Ph.D. i Abstract In a dry ambient,(BaO)x(B2O3)100-x (a pseudo-binary glass system) were synthesized over a wide composition range, 0 mol% < x < 40 mol% , by utilizing induction melting precursors. These high quality glasses were comprehensively examined in Modulated DSC, Raman Scattering, Infrared reflectance experiments. Raman Scattering experiments and the analysis of the symmetric stretch of intra-ring Boron-Oxygen (BO) bonds (A1’) of characteristic “mixed-rings”, permits the identification of Medium Range Structure (MRS) which form in the titled glasses. These modes consist of a triad of modes (705 cm-1, 740 cm-1 and 770 cm-1), and their scattering strengths display a positive correlation to the nucleation of characteristic structural groupings (SGs); analogous to structural groupings found in the corresponding crystalline phases of Barium-Tetraborate (x = 20 mol%), and Barium-Diborate (x = 33 mol%). Identification of the SG’s permit an understanding of the extended range structure apparent in these modified borate glasses. Furthermore, a microscopic understanding of the Immiscibility range in the titled glasses in the 0 mol% < x < 15 mol% range, can be traced to the deficiency of Barium that prohibits nucleation of the Barium-Tetraborate species. (BaO)x[32(B2O3)68(SiO2)]100-x (pseudo-ternary glasses) were synthesized and their Glass Transition Temperature (Tg(x)), molar volume (Vm(x)), and Raman Scattering were examined as a function of modifier (BaO) content in the 25 mol% < x < 48 mol% range. Three distinct regimes of behavior were observed: (1) At low x, 24 mol% < x < 29 mol% range, the modifier largely polymerizes the backbone, and Tg(x) increases. This is a feature that we identify with the stressed-rigid elastic phase. (2)At high x, 32 mol% < x < 48 mol% range, the modifier depolymerizes the network by creating non-bridging oxygen (NBO) atoms; in this regime, Tg(x) ii decreases and networks are viewed to be in the flexible elastic phase. (3) In the narrow intermediate x regime, 29 mol% < x < 32 mol% range, Tg(x) shows a broad global maximum (nearly x-independent), Vm(x) displays a global minimum, and Raman-modes (scattering- strengths and frequencies) become x-independent. These are features that we associate with the isostatically rigid elastic phase (also called the intermediate phase). In this phase, medium range structures adapt as revealed by the counting of Lagrangian bonding constraints and Raman Mode Scattering strengths. iii iv Acknowledgements Pursuing my dreams as a Ph.D. student has been a rewarding, enriching and enlightening experience. I appreciate the time and dedication the committee has devoted to ensure that I contribute a quality Ph.D. Dissertation. This document represents the culmination of years of hard work made possible due to the support provided to me by personal and professional relationships, and I would like to acknowledge these important influences that have fostered and inspired me to achieve my educational goals. First, I would like to thank Dr. Punit Boolchand for the amazing person that you are and for being my mentor for the past 10 years. It is apparent that you truly care about your students and their academic and professional careers. Over the years, I have grown to consider you a part of my family, and without your experience and direction, it would’ve been impossible to navigate the complexities of glass science. It has been inspiring to witness your approach to your career and education, and I will always use this as a guide to my own. Secondly, I would like to thank Dr. Jonathan Goldstein for considering my support on research efforts conducted at the Wright Patterson Air Force Base. Dr. Goldstein, I appreciate your encouragement, your time, and wisdom that you have devoted to me. I have had the pleasure to know you since my Master’s thesis defense in 2003 and look forward to a continued professional relationship. Thank you for the time you have spent in helping me develop my experimental achievements. Next, I would like to thank Dr. John Derov. I appreciate you welcoming me into our Branch on base. I enjoy listening to your wisdom regarding the Physics and the Mathematics of Science. I consider you not only a colleague, but a friend. Thank you for your interest in my work. v I would also like to thank Dr. Peter Kosel for the interesting hallway conversations about Science and course curriculum. I appreciate your individualized approach to teaching and your enthusiasm of the material. I wish more Professors would demonstrate such pride in their work. Thank you for your insightful discussion during my Ph.D. proposal. Furthermore, I would like to thank Dr. Marc Cahay for taking the time to guide me through my Master’s Thesis and now Ph.D. Dissertation. I really appreciate you serving on the committee and appreciate all of the one-on-one conversations that we have had in the past. I would like to thank Dr. Bernard Goodman, Dr. Wayne Bresser and Dr. Andrew Czaja for your help and support. I would also like to thank the students of the past and the present at the University of Cincinnati: Ping Chen, Deassy Novita, Sriram Ravindren, Vignarooban Kandasamy, Shibalik Chakraborty, Kapila Gunasekera, Ralph Chebir, Aaron Welton, Sriram Dash, Somendu Chakraborty, and Chandi Mohanty. I would like to thank my base supervisor, Mark G. Schmitt, for your support of my Ph.D. aspirations. Thank you for your encouragement, trust, and belief that you have had in me. I would like to thank my wife, Paola. You are an amazing mother and you have provided me with so much emotional support. I realize you have lost many valuable hours of sleep in order to listen to my concerns of whether or not I would fall short of my personal goals. Thank you for reassuring me of my abilities and allowing me to appreciate the journey. I would also like to thank my parents, Danny and Sally Holbrook, brother, Jacob Holbrook, and sister-in-law, Kelly Holbrook, for your words of encouragement and constant support. I vi truly admire the way that you conduct your personal and professional lives and use it as a model for my own. Lastly, I would like to thank the Air Force for their support and the support of NSF grant DMR-08-53957. vii Table of Contents CHAPTER 1 INTRODUCTION 1 1.1 Background 1 1.1.1 Topological Constraint Theory 1 1.1.2 Revolutionary Change in Topological Constraint Theory 3 1.2 Relevance of Borate and Silicate Glasses 4 1.3 Findings 8 CHAPTER 2 SAMPLE SYNTHESIS 11 2.1 Barium Borates 11 2.2 Barium Borosilicates 14 CHAPTER 3 THERMAL CHARACTERIZATION 16 3.1 Background for Thermal Characterization Techniques 16 3.1.1 The Dynamic Glass Transition 16 3.1.2 Modulated DSC 18 3.1.3 Frequency Correction 21 3.2 M-DSC Experiments 22 3.3 M-DSC Results 23 3.4 M-DSC Discussion 24 viii CHAPTER 4 DENSITY MEASUREMENTS 26 4.1 Background for Density Measurements 26 4.2 Density Experiments of Barium Borate Glasses 26 CHAPTER 5 OPTICAL CHARACTERIZATION 28 5.1 Background for Optical characterization Techniques 28 5.1.1 Requirements for Raman Active Modes 28 5.1.2 New Picture of Light Interaction 30 5.1.3 Crossing Phenomena of Two Coupled Modes 30 5.1.4 Structure 33 5.1.5 Considerations of Symmetry in Crystalline Materials 34 5.1.6 Symmetry Analysis of Different Symmetry sets of the Meta-borate Crystalline Compound 36 5.1.7 Factor Group Analysis 37 5.1.8 Site Group Analysis 38 5.1.9 Symmetry coordinates, Internal coordinates and Displacement Configurations 40 5.1.10 G-Matrix Example for Familiarity 42 5.1.11 Introduction of a Modifier to the Base Material 44 5.1.12 Mixed Ring Breathing Modes 45 5.1.13 The Raman Line Shape Profile 46 5.2 IR/Raman Experiments of modified Barium Borate Glasses 48 5.2.1 Raman Spectroscopy Experiments 48 ix 5.2.2 Compositioinal Trends of Barium Borate glasses 50 5.2.3 Observations at the Low Frequency Regime Boson and Lattice Vibrations (Extended Range Structure) 53 5.2.4 Observations of BR and Mixed Rings (Medium-Range Structure): Intra-Ring B-O Bonds 53 5.2.5 Observations at the High Frequency Regime: Extra-Ring B-O bonds 53 5.2.6 Mixed Rings and the Intermediate Phase 55 5.2.7 Quantification of Raman Vibrational Mode Characteristics Through Line-shape De-convolution 57 5.2.8 Polarized Raman Experiments 59 5.2.9 Results of Barium Borates 60 5.2.10 FTIR Results 65 CHAPTER 6 DISCUSSION 69 6.1 Topological Phases of Ba-Borate Glasses 69 6.2 Raman Scattering and aspects of Glass-structure 73 6.2.1 Raman scattering as a probe of local, medium-range-structure and extended- range-structure 73 6.2.2 The nature of structural groupings (SGs) contributing to the mixed ring modes observed in Ba Borates 79 6.3 IR reflectance a quantitative probe of B4/B3 content of BaO modified B2O3 86 x 6.4 Microscopic origin of the Immiscibility range in the Equilibrium Phase diagram of the BaO-B2O3 binary 92 6.5 Glass Network dimensionality considerations and the origin of the Boson mode in Borate glasses 95 6.6 Boson mode and the Stress and Rigidity transitions in Ba-borate glasses 100 CHAPTER 7 CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK 102 7.1 Conclusions on (BaO)x(B2O3)100-x binary glass system 102 7.2 Conclusions on (BaO)x[32 (B2O3) 68 (SiO2)]100-x pseudo-ternary glasses 103 7.3 Suggestions for future work 104 CHAPTER 8 APPENDIX THE PUBLISHED WORK ON THE PSEUDO-TERNARY SYSTEM (BAO)X[(B2O3)32(SIO2)68]100-X 106 xi LIST OF FIGURES FIGURE 2-1: PSEUDO-BINARY PHASE DIAGRAM OF THE SYSTEM BAO-B2O3.