U Ottawa L'universite Canadienne Canada's University ITTTT FACULTE DES ETUDES SUPERIEURES ^=1 FACULTY of GRADUATE and ET POSTOCTORALES U Ottawa POSDOCTORAL STUDIES

nm u Ottawa L'Universite canadienne Canada's university ITTTT FACULTE DES ETUDES SUPERIEURES ^=1 FACULTY OF GRADUATE AND ET POSTOCTORALES u Ottawa POSDOCTORAL STUDIES L'UnivensitC' canaiiieraie Canada's university Laura Elizabeth Downie TUTEMDETATH¥SE7M"H6RWTHESTS" ^ScJPh^ics^ GRADE/DEGREE Department of Physics FACULTE, ECOLE, DEPARTEMENT/ FACULTY, SCHOOL, DEPARTMENT Pathways to Recovering Single-Bonded Nitrogen at Ambient Conditions: High Pressure Studies of Molecular and Ionic Azides TITRE DE LA THESE / TITLE OF THESIS Serge Desgreniers DIRECTEUR (DIRECTRICE) DE LA THESE /THESIS SUPERVISOR CO-DIRECTEUR (CO-DIRECTRICE) DE LA THESE / THESIS CO-SUPERVISOR Zibgniew Stadnik Ravi Bhardwaj David Sinclair Gary W. Slater Le Doyen de la Faculte des etudes superieures et postdoctorales / Dean of the Faculty of Graduate and Postdoctoral Studies Pathways to Recovering Single-Bonded Nitrogen at Ambient Conditions: High Pressure Studies of Molecular and Ionic Azides Laura E. Downie Thesis submitted to the Faculty of Graduate and Postdoctoral Studies In partial fulfillment of the requirements for the degree of Master of Science in Physics Department of Physics Faculty of Science University of Ottawa ©Laura E. Downie, Ottawa, Canada, 2010 Library and Archives Bibliotheque et 1*1 Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A 0N4 OttawaONK1A0N4 Canada Canada Your Tile Votre reference ISBN: 978-0-494-74182-5 Our file Notre reference ISBN: 978-0-494-74182-5 NOTICE: AVIS: The author has granted a non L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distribute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. 1+1 Canada Abstract Working towards the goal of recovering single-bonded nitrogen at ambient conditions, the approach taken in this work is to subject nitrogen-rich molecular and ionic azides (specifically, cyanuric triazide and ammonium azide) to high pressures to induce transitions to phases that contain single-bonded nitrogen. The samples were subjected to extreme pressures using a diamond anvil cell and subsequently studied using high-resolution synchrotron powder x-ray diffraction and vibrational Raman spectroscopy. The experimental results indicate that both cyanuric triazide and ammonium azide undergo a pressure-induced first order structural phase transition at 30 and 3.0 GPa, respectively. The analyses and characterizations of these dense energetic materials are discussed in detail, and will be used to explore the possibility of recovering single-bonded nitrogen at ambient conditions. u Statement of Originality To the best of my knowledge, I certify that the research presented in this thesis is the original work of the author. Any contributions to this work made by others with whom I have worked are expressly indicated and acknowledged in the text. 111 Acknowledgements First of all, I would like to thank Prof. Serge Desgreniers for his supervision over the past two years, and for giving me the opportunity to work on such a dynamic and interesting project. I would also like to thank Dr. Ning Chen and Dr. Chang-Yong Kim, Hard X-ray MicroAnalysis beamline scientists at the Canadian Light Source for their help in carrying out x-ray diffraction experiments. Of course there wouldn't have been much of a project if we didn't have the right starting materials. In this regard, I would like to acknowledge Prof. Muralee Murugesu (University of Ottawa, Department of Chemistry) and his graduate student Didier Savard for the chemical synthesis of cyanuric triazide and ammonium azide. Heading up this project were Dr. Anguang Hu and Dr. Fan Zhang (Defence Research and Development Canada - Suffield) whose seemingly endless enthusiasm is certainly contagious. The theoretical calculations performed at DRDC not only provided the motivation for this work, but significantly helped in the interpretation of the experimental results. Their willingness and eagerness to help is certainly appreciated. Last, but undoubtedly not least, I would like to sincerely thank my colleague Dr. Jesse Smith. If I ever needed anything or just had a "quick" question, he always made the time to help and was always happy to do so. For his many insights, his camaraderie during the long night shifts at the CLS, his incredible patience, and of course, for bringing humour to the lab, thank you does not begin to cover it, but it's a start. Thank you. iv Table of Contents Abstract ii Statement of Originality iii Acknowledgements iv Table of Contents v List of Figures viii List of Tables xv Nomenclature xvi Chapter 1 Introduction 1 Chapter 2 Literature Review and Motivation 4 2.1 Energetic Materials 4 2.1.1 A brief introduction to energetic materials 4 2.1.2 Development of new energetic materials 5 2.1.3 Energetic materials at extreme conditions 7 2.2 Single-Bonded Nitrogen 8 2.2.1 Theoretical predictions of polymeric nitrogen 8 2.2.2 Experimental confirmation 10 2.2.3 Recovery to ambient conditions 12 2.3 High Pressure High Nitrogen Content Materials as Sources of Single-Bonded Nitrogen 13 2.3.1 Sodium azide 14 2.3.2 Lithium azide 16 2.3.3 N2-H2 mixtures 16 2.4 Motivation and Scope of This Work 18 2.4.1 Cyanuric triazide 18 2.4.2 Ammonium azide 22 2.5 Studying Materials at High External Pressures 25 2.5.1 Phase stability and phase transitions 26 2.5.2 Isothermal equations of state 28 References 32 v Chapter 3 Experimental Methods 37 3.1 Diamond Anvil Cell 37 3.1.1 Introduction and overview 37 3.1.2 Anvils 39 3.1.3 Gasket and sample chamber 42 3.1.4 Seats 44 3.1.5 Cell body 45 3.2 Measuring Pressure 46 3.3 Vibrational Raman Spectroscopy 50 3.3.1 Raman scattering 51 3.3.2 Experimental setup 53 3.4 Angle-Dispersive Powder X-Ray Diffraction Using Synchrotron Radiation 55 3.4.1 A brief introduction to x-ray diffraction 55 3.4.2 Necessity of synchrotron radiation use 59 3.4.3 Experimental configuration at the Hard X-ray MicroAnalysis Beamline of the Canadian Light Source 62 3.4.4 Data acquisition and processing 65 3.4.5 Diffraction pattern analysis 69 References 72 Chapter 4 Cyanuric Triazide 74 4.1 Sample Preparation 74 4.1.1 Chemical synthesis 74 4.1.2 Sample preparation and loading into the diamond anvil cell 75 4.2 Sample Stability 76 4.2.1 Laser-induced reaction 76 4.2.2 Decomposition upon the application of pressure 77 4.3 Raman Spectroscopy Results 82 4.3.1 Ambient pressure Raman spectrum 83 4.3.2 Low pressure Raman results 86 4.3.3 High pressure Raman results 88 4.4 Powder X-Ray Diffraction Results 91 4.4.1 Ambient pressure diffraction results 92 4.4.2 Diffraction results as a function of pressure 94 4.4.3 Low pressure phase 97 4.4.4 High pressure phase 99 4.4.5 Decompression studies 103 vi 4.5 Discussion 105 4.5.1 Phase 1 105 4.5.2 Phase II 106 References 109 Chapter 5 Ammonium Azide 110 5.1 Sample Preparation 110 5.1.1 Chemical synthesis 110 5.1.2 Sample preparation and loading into the diamond anvil cell Ill 5.2 Sample Stability 112 5.3 Raman Spectroscopy Results 113 5.3.1 Ambient pressure Raman spectrum 114 5.3.2 High pressure Raman results 116 5.4 Powder X-Ray Diffraction Results 119 5.4.1 Near-ambient pressure diffraction results 121 5.4.2 Diffraction results as a function of pressure 123 5.4.3 Low pressure phase 126 5.4.4 High pressure phase 128 5.4.5 Decompression studies 135 5.5 Discussion 136 5.5.1 Phase transition 136 5.5.2 Phase II 137 References 139 Chapter 6 Summary and Future Work 140 Appendix A Copyright permissions Al vii List of Figures Figure 1.1: Molecular structures of the two azides studied in this work: cyanuric triazide (left) and ammonium azide (right) 2 Figure 2.1: Molecular structure of some commonly used energetic materials: (a) nitroglycerine, (b) TNT, (c) RDX, (d) HMX,and (e) CL-20 5 Figure 2.2: Calculated total energies per atom for several candidate structures of single- bonded nitrogen compared to molecular nitrogen, showing the stability (lowest energy) of the cubic gauche structure at small atomic volumes (high pressures).

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