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Magnetism of Carbon Nanostructures and in Situ TEM Dynamic Transformations of Carbon-Based Nanomaterials

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Magnetism of Carbon Nanostructures and in Situ TEM Dynamic Transformations of Carbon-Based Nanomaterials INSTITUTO POTOSINO DE INVESTIGACION´ CIENT´IFICA Y TECNOLOGICA,´ A.C. POSGRADO EN CIENCIAS APLICADAS Magnetism of carbon nanostructures and in situ TEM dynamic transformations of carbon-based nanomaterials Tesis que presenta Julio Alejandro Rodr´ıguezManzo Para obtener el grado de Doctor en Ciencias Aplicadas En la opci´onde Nanociencias y Nanotecnolog´ıa Codirectores de la Tesis: Dr. Humberto Terrones Maldonado Dr. Mauricio Terrones Maldonado Dr. Florentino L´opez Ur´ıas San Luis Potos´ı,S.L.P., febrero de 2007. Constancia de aprobaci´onde la tesis La tesis Magnetism of carbon nanostructures and in situ TEM dynamic transformations of carbon-based nanomaterials presentada para obtener el Grado de Doctor en Ciencias Aplicadas en la opci´onNanociencias y Nanotec- nolog´ıafue elaborada por Julio Alejandro Rodr´ıguezManzo y aprobada el 1 de febrero de 2007 por los suscritos, designados por el Colegio de Profesores de la Divisi´onde Materiales Avanzados del Instituto Potosino de Investigaci´onCient´ıfica y Tecnol´ogica,A.C. ——————————————————— ——————————————————— Dr. Humberto Terrones Maldonado Dr. Mauricio Terrones Maldonado Codirector de la tesis Codirector de la tesis ——————————————————— ——————————————————— Dr. Florentino L´opez-Ur´ıas Dr. Emilio Mu˜nozSandoval Codirector de la tesis Comit´etutorial iii Cr´editosinstitucionales Esta tesis fue elaborada en la Divisi´onde Materiales Avanzados del Instituto Potosino de Investigaci´onCient´ıficay Tecnol´ogica,A.C., bajo la codirecci´onde los doctores Humberto Terrones Maldonado, Mauricio Terrones Maldonado y Florentino L´opez-Ur´ıas. Durante la realizaci´ondel trabajo el autor recibi´ouna beca acad´emicadel Con- sejo Nacional de Ciencia y Tecnolog´ıa (No. de registro 172777) y del Instituto Potosino de Investigaci´onCient´ıficay Tecnol´ogica,A. C. v Acknowledgments Anybody who knows about the subject will say that searching for a good advisor is a difficult task. Finding two, in quantum mechanics terms, is highly improbable. If both are brothers, good luck must be involved. During these years, Humberto and Mauricio Terrones have been excellent advisors. Always available in their office, they transmitted their joy for science and research and made me feel part of the scientific community dedicated to the study of carbon nanostructures that goes back to Alan Mackay and Harry Kroto, among others, and continues with them. My gratitude to both. The advice given by Florentino L´opez was fundamental for obtaining results on the magnetic properties of carbon nanostructures. I thank him for his willingness to share his programming knowledge, as well as his availability to work as a team. In addition, I thank him and Emilio Mu˜nozfor their generosity: they shared their office with me during the 99% of my stay at IPICYT. The time at IPICYT would have been less fortunate without the support, the share frustration and the enthusiasm of my fellow travelers: Ana Laura El´ıasand Adalberto Zamudio, to whom I am grateful. Also, I wish to acknowledge Jos´eRomo, for being there to hear and talk about ideas related to carbon nanostructures, among other subjects; Eduardo Cruz, for his help with anything related to my computer’s software; David Meneses, who helped me in the analysis of X ray data, and saved me from a row in Guanajuato; and Xavier Lepr´o,who at the end of this stage helped me with everything about Latex. One of the most pleasing aspects of carrying out scientific research is the pos- sibility to meet people in different places who are more than happy to share their expertise and knowledge. I thank David Smith, Martha McCartney and Lin Gu from Arizona State University, for being there to teach me the different techniques that can be used in the transmission electron microscope (TEM). It was during the ix winter school in electron microscopy at ASU that I was first introduced to the ex- citing aspects of this technique. I also thank Manfred R¨uhlefor his invitation to carry out both the synthesis and characterization of single-walled carbon nanotubes at the Max-Planck-Institut f¨urMetallforschung in Stuttgart, where Fabio Lupo was an outstanding host, and I thank him for that. Also, I am grateful to Gerd Kurt Reiband, Juan Jos´eVilatela and Felipe Cervantes for their help to realize quenching experiments at the Santa Rita laboratory. I thank Paola Ayala for her invitation to participate in a series of experiments to deposit nanoparticles on nitrogen-doped carbon nanotubes. The experiments of nanotube electron irradiation in the TEM were motivated by the innovative previous work of Florian Banhart. I thank him for his kind invitation to the University of Mainz, where he shared, enthusiastically, his experience. I thank also Litao Sun who helped me with the irradiation experiments. For the essential technical assistance needed in a laboratory –and even more in a laboratory under construction– I am grateful to Lisette Noyola, Grisel Ram´ırezand Daniel Ram´ırez.I thank Adolfo Mart´ınezfor his support with everything related to Linux. I thank Gabi P´erezAssaf for helping me to elucidate terms and procedures of the complex administration world. For financial support I thank the following institutions: CONACYT, IPICYT, Max-Planck-Institut f¨urMetallforschung, Max-Planck-Institut f¨urPoly- merforschung/Universit¨atMainz and Arizona State University. Anybody who finds this thesis readable should acknowledge, as I do, the effort carried out by Faith Coldren to edit this work: thanks. Finally, I would like to thank mi sister Olga, my brothers Joaqu´ıny Claudio, and my parents Olga y Joaqu´ın.Not only they have indulged my interest in science, but each, in his or her own way, as nurtured it. x Contents Acknowledgments .............................. ix List of Tables ................................. xv List of Figures . xvii Resumen ....................................xxi Abstract . xxiii Preface .....................................xxv 1 General introduction 1 1.1 Carbon nanostructures and related materials . 1 1.1.1 spn hybridizations in carbon . 2 1.1.2 Carbon allotropes . 3 1.2 The concept of curvature . 6 1.3 Magnetism of curved carbon nanostructures . 8 1.4 Electron irradiation of carbon nanostructures . 9 1.5 Organization of the thesis . 9 References . 11 2 Magnetic response of π-electrons 15 2.1 Introduction . 15 2.2 Magnetism of carbon allotropes . 16 2.3 Coalescence of C60 and carbon nanotori . 20 2.3.1 Coalescence of C60 ........................ 20 2.3.2 Carbon nanotori . 21 2.3.3 Corrugated carbon nanotori . 24 2.4 The London theory . 26 xi 2.5 Benzene, C60 and C70: case studies . 28 2.6 Polymerized C60 and C70 molecules . 32 2.7 Nanotori from SWNT (only hexagonal rings) . 38 2.8 Corrugated nanotori (heptagonal and octagonal rings) . 41 2.8.1 Tori C60-C2(8) . 43 2.8.2 Tori C60-C3(7) . 44 2.8.3 Tori C60-C5(8) . 45 2.9 Doped carbon nanotori . 46 2.10 Topologically complex carbon nanostructures . 52 2.11 Conclusions . 53 References . 55 3 Synthesis of different types of CNTs 59 3.1 Introduction . 59 3.2 Carbon nanotube growth methods . 60 3.3 Pyrolysis of aerosolized solutions . 61 3.3.1 Injection aerosol generator . 62 3.3.2 Ultrasonic aerosol generator . 63 3.4 Characterization techniques . 63 3.5 Single-walled carbon nanotubes (SWNTs) . 64 3.5.1 Experimental conditions . 64 3.5.2 SEM and TEM analysis . 65 3.5.3 Raman spectroscopy of SWNTs . 67 3.5.4 SWNT growth model . 70 3.6 Multi-walled carbon nanotubes . 71 3.6.1 Experimental conditions . 72 3.6.2 Characterization of MWNTs . 72 3.6.3 MWNT growth model . 74 3.7 Growth of nitrogen-doped MWNTs . 74 3.7.1 Experimental conditions . 75 3.7.2 Characterization of CNx ..................... 75 3.8 Metal inclusions inside MWNTs . 78 xii 3.8.1 Fe@MWNTs . 78 3.8.2 Co@MWNTs . 79 3.8.3 Ni@MWNTs . 83 3.8.4 FeCo@MWNTs . 86 3.9 Conclusions . 88 References . 90 4 TEM modifications of MWNT-based nanostructures 95 4.1 Introduction . 95 4.2 Electron irradiation effects in solids . 96 4.2.1 Electron irradiation effects in carbon nanostructures . 99 4.2.2 Thermal annealing of defects induced by electron irradiation . 104 4.3 Experimental conditions . 107 4.4 MWNTs as high pressure cells and nanoextruders . 107 4.4.1 Experimental observations . 108 4.4.2 Mechanism of pressure buildup . 113 4.5 Carbon nanotube growth . 115 4.5.1 SWNT growth . 116 4.5.2 MWNT growth . 118 4.5.3 Possible nanotube growth mechanism . 121 4.6 MWNT-metal-MWNT junctions . 123 4.6.1 Formation of MWNT-metal-MWNT junctions . 123 4.6.2 Rupture of MWNT-metal-MWNT junctions . 127 4.7 Coda: curvature in carbon nanostructures . 129 4.8 Conclusions . 131 References . 133 5 Conclusions and future work 139 5.1 Conclusions . 139 5.2 Future work . 141 Published articles ..............................143 xiii List of Tables 2.1 Ring current χ and maximum iij for C60 and C70 . 31 2.2 Ring current χ and maximum iij for C60 dimers . 33 2.3 Ring current χ and maximum iij for nC60-C5(8) and nC70-C5(8) lin- ear chains . 36 max 2.4 Maximum inter-atomic currents iij for corrugated carbon nanotori . 42 4.1 Threshold energies for graphite . 99 4.2 Formation and migration energies for interstitials and vacancies in graphite . 102 4.3 Diffusion rates of carbon interstitials . 105 xv List of Figures 1.1 Different spn hybridizations in carbon . 2 1.2 Allotropes of carbon . 3 1.3 Notation (n, m) to classify SWNTs . 5 1.4 Surfaces, carbon lattices and carbon nanostructures with different Gaussian curvature . 7 2.1 Ring current pattern in anthracene . 17 2.2 Electron microscopy images of carbon nanotubes . 18 2.3 Rhombohedral C60 ...........................
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