Deformation of Hexagonal Boron nitride A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy (PhD) in the Faculty of Science and Engineering 2018 Abdulaziz N. Alharbi School of Materials Faculty of Science and Engineering The University of Manchester, UK Table of contents LIST OF FIGURES ............................................................................................................... 6 LIST OF TABLES ............................................................................................................... 17 ABSTRACT ...................................................................................................................... 19 DECLARATION ................................................................................................................ 20 COPYRIGHT STATEMENT ................................................................................................. 21 ACKNOWLEDGEMENTS ................................................................................................... 22 CHAPTER 1: INTRODUCTION ........................................................................................... 23 1.1 AIMS AND THESIS STRUCTURE ................................................................................................ 25 CHAPTER 2: LITERATURE REVIEW .................................................................................... 27 2.1 INTRODUCTION ................................................................................................................... 27 2.2 STRUCTURES ....................................................................................................................... 27 2.2.1 Hexagonal boron nitride ......................................................................................... 27 2.2.2 Boron nitride nanosheets (BNNSs) .......................................................................... 30 2.2.3 Boron nitride nanotubes (BNNTs) ........................................................................... 32 2.3 SYNTHESES ......................................................................................................................... 34 2.3.1 Hexagonal boron nitride (h-BN) .............................................................................. 35 2.3.2 Boron nitride nanosheets (BNNSs) .......................................................................... 36 2.3.2.1 Self-Assembly ............................................................................................................... 36 2.3.2.2 Mechanical cleavage .................................................................................................... 37 2.3.2.3 Chemical exfoliation .................................................................................................... 38 2.3.2.4 Other methods ................................................................................................................ 39 2.3.3 Boron nitride nanotubes (BNNTs) ........................................................................... 42 2.3.3.1 Arc discharge ................................................................................................................ 42 2.3.3.2 Laser ablation ............................................................................................................... 42 2.3.3.3 Carbothrmal methods .................................................................................................. 43 2.3.3.4 Chemical vapour deposition (CVD) .............................................................................. 45 2.3.3.5 The inductive thermal plasma method ........................................................................ 46 2.3.3.6 Other methods ............................................................................................................. 49 2 2.4 PROPERTIES ........................................................................................................................ 50 2.4.1 Optical properties ................................................................................................... 50 2.4.2 Mechanical properties ............................................................................................ 51 2.5 APPLICATIONS ..................................................................................................................... 56 2.5.1 Nanocomposites ..................................................................................................... 56 2.5.1.1 Filler geometry ............................................................................................................. 58 2.5.1.2 Micromechanical models for estimating the elastic modulus of a composite ............ 63 2.5.1.3 Mechanisms of mechanical enhancement in nanocomposites ................................... 66 CHAPTER 3: RAMAN BANDS CHARACTERISATION OF HEXAGONAL BORON NITRIDE (H-BN) MATERIALS ..................................................................................................................... 68 3.1 INTRODUCTION ................................................................................................................... 68 3.2 THEORY OF THE RAMAN EFFECT .............................................................................................. 69 3.3 RAMAN ACTIVE BANDS OF (H-BN) MATERIALS ........................................................................... 72 3.4 STRAIN EFFECTS ON THE RAMAN BAND MODES OF BN MATERIALS ................................................. 78 CHAPTER 4: MATERIALS AND EXPERIMENTAL TECHNIQUES ............................................ 82 4.1 MATERIALS ........................................................................................................................ 82 4.2 CHARACTERISATION TECHNIQUES OF THE BORON NITRIDE MATERIALS ............................................. 82 4.2.1 Optical Microscopy ................................................................................................. 82 4.2.2 Electron Microscopy (SEM and TEM) ...................................................................... 84 4.2.3 Raman Spectroscopy ............................................................................................... 86 4.2.4 Atomic Force Microscopy (AFM) ............................................................................. 86 4.2.5 X-ray diffraction (XRD) ............................................................................................ 87 4.3 SAMPLE FABRICATION ........................................................................................................... 89 4.3.1 Mechanical cleavage............................................................................................... 89 4.3.2 Liquid Exfoliation ..................................................................................................... 91 4.3.3 Glass matrices and BN/glass commposites ............................................................ 92 4.4 EXPERIMENTAL PROCEDURE FOR THE DEFORMATION OF BN MATERIALS ........................................ 94 CHAPTER 5: CHARACTERISATION OF HEXAGONAL BORON NITRIDE (H-BN) MATERIALS ... 97 5.1 INTRODUCTION ................................................................................................................... 97 5.2 SINGLE CRYSTAL OF HEXAGONAL BORON NITRIDE (H-BN) AND EXFOLIATED H-BN FLAKES ................... 97 3 5.2.1 Optical microscopy .................................................................................................. 97 5.2.2 Raman spectroscopy ............................................................................................... 99 5.3 BORON NITRIDE (BN) POWDER AND EXFOLIATED BN SHEETS ..................................................... 100 5.3.1 X-ray diffraction (XRD) .......................................................................................... 100 5.3.2 Scanning electron microscopy (SEM) .................................................................... 101 5.3.3 Transmission electron microscopy (TEM) ............................................................. 103 5.3.4 Atomic force microscopy (AFM) ............................................................................ 103 5.3.5 Optical microscopy ................................................................................................ 104 5.3.6 Raman spectroscopy ............................................................................................. 106 5.4 BORON NITRIDE NANOTUBE BUCKYPAPER AND EXFOLIATED BNNTS ............................................. 108 5.4.1 Scanning electron microscopy (SEM) .................................................................... 108 5.4.2 Transmission electron microscopy (TEM) ............................................................. 109 5.4.3 X-ray diffraction (XRD) .......................................................................................... 110 5.4.4 Optical microscopy ................................................................................................ 111 5.4.5 Raman spectroscopy ............................................................................................. 112 5.5 SUMMARY ....................................................................................................................... 113 CHAPTER 6: DEFORMATION OF HEXAGONAL BORON NITRIDE (H-BN) ........................... 115 6.1 INTRODUCTION ................................................................................................................