ABSTRACT DILL, ERIC DELAMARTER. Determining Melt-Crystallization Mechanisms and Structures of Disordered Crystalline Solids. (Under the direction of James D. Martin). The crystal growth kinetics of the halozeotype CZX-1 were explored with a series of isothermal crystallization experiments performed with Differential Scanning Calorimetry (DSC) and 2-D Temperature and time Resolved X-ray Diffraction (2-D TtXRD). Fitting the transformations to the well-known Kolmogorov-Johnson-Mehl-Avrami (KJMA) reaction model resulted in rate constants that appeared to be strongly dependent upon the sample size. Crystal growth simulations were designed to elucidate the relationship between the observed crystal growth rate and the sample size. These simulations unequivocally demonstrated that the KJMA rate constant is highly dependent on the sample size and the sample shape. Under the simulated conditions of slow nucleation relative to crystal growth, sample volume and sample anisotropy correction affords a means to eliminate the experimental condition dependence of the KJMA rate constant, producing the material specific parameter, the velocity of the phase boundary. Additionally, the crystallization simulations allow us to clearly define the KJMA parameters: t0 is nominally the induction time of the first crystallite in the system; n is the dimensionality of the transformation process; k, when volume and anisotropy is accounted for, is equivalent to the crystallization phase boundary velocity within a factor of two. The nucleation process in CZX-1 was explored from the “bulk” perspective with DSC and radially integrated TtXRD. No evidence for nucleation according to the mechanism proposed by Classical Nucleation Theory was found. However, a maximum in the initial nucleation “rate” was observed, defined as the inverse of the initial nucleation time from the -1 KJMA model: knuc=t0 . A method for direct analysis of the 2D TtXRD diffraction images is presented where the intensity of individual diffraction spots are fit to the KJMA model to determine their t0 and knuc values. The direct analysis of 2D diffraction images demonstrates the capability to quantitatively estimate the number of crystallites that appeared during an isothermal crystallization experiment. The structure of the plastic crystalline carbon tetrabromide, -CBr4 was investigated as a potential model of the structure of the phase boundary between liquid and crystalline phases. Two-dimensional single-crystal synchrotron X-ray diffraction of the high-temperature plastic phase of carbon tetrabromide (α-CBr4, 퐹푚3̅푚, a≈8.82 Å) was collected which reveals a twinned plastic crystal and twinned structured diffuse scattering with sharp 푮 ± {110}∗ sheets of diffuse intensity (where G represents the set of 퐹푚3̅푚 Bragg reflections). The real- space manifestation of the intense and highly structured diffuse scattering is demonstrated through 2D Patterson Function analysis. The structural understanding is augmented by a series of simulations. The analysis of the diffraction images and the simulations suggest that the CBr4 units reside in D2d site symmetry on average, consistent with previous reports. All these structural analyses find that the structure of α-CBr4 is well-described by static disorder, in clear contrast to the commonly accepted notion of the plastic phase possessing dynamic reorientational freedom. © Copyright 2014 Eric Dill All Rights Reserved Determining Melt-Crystallization Mechanisms and Structures of Disordered Crystalline Solids by Eric Delamarter Dill A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Chemistry Raleigh, North Carolina 2014 APPROVED BY: _______________________________ ______________________________ James D. Martin David A. Shultz Committee Chair ________________________________ ________________________________ Mike H. Whangbo Paul A. Maggard DEDICATION This work is dedicated to my incredible parents and my amazing wife, without whom none of this would have been possible. ii BIOGRAPHY Eric was born August 9th, 1895 in Memphis, Tennessee to parents Robert and Kristen Dill. Eric grew up in Raleigh, North Carolina and went through the Magnet program of the Wake County Public School System. He attended the John W. Ligon GT Magnet Middle school and William G. Enloe Magnet High School. He went to North Carolina State University where he pursued degrees in Chemistry and Physics. Eric began working with Professor Jim Martin as an undergraduate researcher in the 2006 when they crossed paths in Jim's Inorganic Chemistry 1 course. Eric remained at North Carolina State University to pursue a graduate degree in Inorganic Chemistry with Jim after completing his undergraduate studies. Good thing he decided to stay at NC State for graduate school because he met his amazing wife while in graduate school. iii ACKNOWLEDGEMENTS First and foremost, this work is a testament to the dedication to teaching and mentoring of my advisor, Jim. Your open door policy provides so much support to your graduate students (though I suppose you know this). I always felt that I could come ask you questions and knew that you wouldn’t feel bothered or put out by having us come ask you questions. Every day I knew I would learn something new from you, be it in the classroom while I was your TA, at group meeting, or during the course of one of our countless rounds of debate over crystallization and disorder. You taught me what it means to be a scientist by proving guidance when I needed it most and giving me the intellectual freedom of self-discovery. Jaap, my dissertation is also a testament to your open door policy and willingness to (almost always) drop everything to teach me about things that can be done with statistics that seem more like voodoo than math, to teach me about the black magic of fourier transforms and sometimes just to debate the finer points of esoteric phase transition theory (Landau, anyone?) Your ability to play devil’s advocate is unparalleled and therefore, simply put, maddening, because you’re so freaking good at it. Every time I thought I had come to a reasonable solution, you would find a clever way to poke a hole in it. I knew that I could always come to you with questions and you would always be excited to dive into the weeds. Thank you Jim and Jaap. Without these two brilliant men, the research reported in this dissertation would most certainly not have been possible. Both of you have taught me what it means to be a great teacher. Your passion for teaching and your desire to watch students succeed is inspiring. Thank you. Thank you to the Martin Group members, past and present, especially Feier, whose love of all things cute always provided a much needed break from disorder and mechanisms. Your herculean effort to beat the hydra (i.e., DSC crystallization kinetics) into reliable results proved to be a cornerstone of the crystallization mechanism research. Every time you thought you were done with that analysis, two more heads sprang up. Thank you to Amanda for being a wonderful mentor and friend and for paving the way with the crystallization mechanism studies. Thank you to Brad for becoming our resident expert in all things computationally quantum and keeping me honest about my appreciation for the dark magic of computational iv quantum mechanics! Best of luck with that zinc chloride hydrate structure and remember, if it’s yellow, let it mellow. Thank you to the wacky and wild cast of undergraduate researchers that I’ve worked with over the years. Eric R., you’re one of the finest people I’ve ever met and it was wonderful to be able to work with and mentor you over the years. Elijah, I wish we had a chance to work together more, but best of luck in graduate school! I know you guys will do incredible things. To Mick the pirate; keep doing your thing because you’re awesome at it. I will most certainly miss those days when I walk into the lab and there’s a pirate carefully tinkering with the microbalance. James, keep on doing your thing. You’ve got the incredible gift of creating seemingly magical devices from everyday things. That dip-probe spectrometer will probably amaze me until the day I die. Daniel, even though your time with us at NC State was short and you’ll likely return to Brown to finish your studies, you’re the most dedicated undergraduate student I’ve ever met and your work ethic is unparalleled. I know you’ll be successful at whatever you set your mind to. Perhaps you’ve got enough baseball gloves though? Troy, though we only had limited interaction, I feel comfortable advising you to watch out for exploding (or was it an implosion?) drybox gloves. It’s been an absolute treat to work with all of you over the years. Please consider me a resource to pull from whenever you need and let me know if I can ever be of assistance! (Brad and Feier, that goes for you too!) Thank you to Dave B. and Rob K., who were always willing to listen to me babble on about crystallization mechanisms and disordered materials, even when you would rather be doing (literally) almost anything else. Thank you to Justin K. for being a great friend and overnight-work-companion when we ended up on the same weird schedule while I was writing my prelim and you were writing your dissertation. Thank you to those of you who participated in those weekly morning meetings and the biweekly writing workshops in the spring semester of 2013 (Michael, Meghan, Alecia, Ryan, Sandra, Suzanne, Timia, Rhonda and Mike). Those meetings took quite a lot of the sting out of the dissertation writing process. Finally, thank you to my committee members: Dr. Mike Whangbo, Dr. David Shultz, Dr. Paul Maggard and Dr. Mike Carter; for taking the time to read this document and for taking v part in my final defense.