Atomic Scale Characterization and First-Principles Studies of Si3N4 Interfaces (eBook)

Weronika Walkosz (Autor)

eBook Download: PDF

2011 | 2011
XIV, 110 Seiten
Springer New York (Verlag)
978-1-4419-7817-2 (ISBN)

Infos

This thesis presents results from a combined atomic-resolution Z-contrast and annular bright-field imaging and electron energy loss spectroscopy in the Scanning Transmission Electron Microscopy, as well as first principles studies of the interfaces between crystalline ??Si₃N₄ and amorphous (i) CeO2-x as well as (ii) SiO2 intergranular film (IGF).  These interfaces are of a great fundamental and technological interest because they play an important role in the microstructural evolution and mechanical properties of Si3N4 ceramics used in many high temperature and pressure applications.  The main contribution of this work is its detailed description of the bonding characteristics of light atoms, in particular oxygen and nitrogen, at these interfaces, which has not been achieved before.  The atomic-scale information on the arrangement of both light and heavy atoms is critical for realistic modeling of interface properties, such as interface strength and ion transport, and will facilitate increased control over the performance of ceramic and semiconductor materials for a wide-range of applications.

Inhalt

Supervisor’s Foreword 6
Acknowledgments 9
Contents 10
1 Silicon Nitride Ceramics 13
1.1…Introduction 13
1.2…Overview of Previous Studies on Si3N4 14
1.3…Overview of the Present Study 15
References 17
2 Theoretical Methods and Approximations 23
2.1…Born Oppenheimer Approximation 23
2.2…Density Functional Theory 24
2.3…Approximations for the Exchange-Correlation Energy Functional 26
2.4…Periodic Systems: Bloch’s Theorem 27
2.5…k-Point Sampling 28
2.6…Plane Waves, Pseudopotentials, and the Projector Augumented Wave Method 29
2.7…Aperiodic Structures 30
2.8…DFT+U 31
References 32
3 Overview of Experimental Tools 34
3.1…Conventional Transmission Electron Microscope 34
3.2…High-Resolution TEM 35
3.3…Image Simulations 37
3.4…Z-Contrast Imaging in STEM 38
3.5…Annular Bright-Field Imaging in STEM 40
3.6…Probe Formation 40
3.7…Electron Energy-Loss Spectroscopy/Energy-Filtered STEM 44
3.8…Aberration Correctors 47
3.9…Microscopes Used 49
3.10…Multivariate Statistical Analysis 50
References 51
4 Structural Energetics of beta -/bf{Si}_3/hbox{N}_4(10/overline{1}0) Surfaces 55
4.1…Introduction 55
4.2…Computational Methods and Parameters 56
4.3…Silicon Nitride in the Presence of Oxygen 57
4.3.1 /Uptheta={/frac{1}{4}} ML Coverage 59
4.3.2 /Uptheta={/frac{1}{2}} ML Coverage 60
4.3.3 /Uptheta={/frac{3}{4}} ML Coverage 63
4.3.4 /Uptheta=1 ML Coverage 65
4.3.5 Phase Diagram of /varvec /beta-/bf{Si}_3/hbox{N}_4/,(10/overline{1}0) Surface 66
4.3.6 Summary 69
4.4…Silicon Nitride in the Presence of Cerium 70
4.5…Silicon Nitride in the Presence of Oxygen and Rare-Earth Elements 72
4.5.1 Summary 74
References 74
5 Atomic-Resolution Study of the Interfacial Bonding at Si3N4/CeO2minus delta Grain Boundaries 76
5.1…Experimental Setup 76
5.2…Z-Contrast Images of Si3N4/CeO2minusdelta Interfaces 77
5.3…EELS Experiments 79
5.4…Summary 81
References 82
6 Atomic-Resolution Study of {/varvec /beta}-/bf{Si}_3/bf{N}_4//bf{SiO}_2 Interfaces 83
6.1…Introduction 83
6.2…Methods 84
6.3…Imaging of the /bf{Si}_3/bf{N}_4//bf{SiO}_2 Interface 84
6.3.1 Spectroscopy 87
6.4…Thicker Intergranular Films 93
6.5…Discussion of the Results and Conclusions 95
References 96
7 Imaging Bulk alpha -Si3N4 98
7.1…Introduction 98
7.2…Experimental Setup 99
7.2.1 Imaging alpha -Si3N4 99
7.2.2 DFT Calculations 100
7.2.3 EELS Experiments 102
7.3…Summary 102
References 103
8 Conclusions and Future Work 104
References 107
Appendix A Projector Augmented Wave Method 108
Appendix B Incoherent Imaging 111
Index 113

Produkt-Details

• Erscheint lt. Verlag: 6.4.2011
• Reihe/Serie: Springer Theses
• Reihe/Serie: Springer Theses
• Zusatzinfo: XIV, 110 p.
• Verlagsort: New York
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie ► Analytische Chemie
• Themenwelt: Naturwissenschaften ► Chemie ► Physikalische Chemie
• Themenwelt: Naturwissenschaften ► Chemie ► Technische Chemie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik ► Maschinenbau
• Schlagworte: Born Oppenheimer approximation • Electron Energy Loss Spectroscopy • experimental tools • interfacial bonding • Multivariate Statistical Analysis • PlaneWaves • Projector Augumented Wave Method • Pseudopotentials • Si3N4 • Silicon nitride ceramics
• ISBN-10: 1-4419-7817-8 / 1441978178
• ISBN-13: 978-1-4419-7817-2 / 9781441978172