Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...

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22 Fig. 2.19. The modification of the diffraction pattern due to twinning in a crystal with the electron beam along the (from Hirsch et al. (1965)) The final orientation of a twin platelet and corresponding twin spots may be obtained, in the case of fcc crystals, by a 180° rotation of the lattice about the {111} planes. This is seen by rotating the diffraction pattern from the perfect crystal by 180° and superimposing it onto the original (Fig. 2.17). This example is called primary twinning in fcc materials. 2.9 Vacancy and Interstitial Loops If a material contains a concentration of vacancies and interstitials in excess of the equilibrium concentration these point defects may diffuse and coalesce to form clusters and precipitate as platelets which will collapse to form a dislocation loop as they grow larger as shown in Fig. 2.20.
23 Fig. 2.20. The process of vacancy loop formation in a lattice (from Hull et al. (1984)) This figure depicts the process for vacancy loop formation. The vacancies cluster to form a platelet with the subsequent collapse of the planes inward to form a dislocation loop. The dislocation loop may under certain conditions enclose an area constituting a stacking fault. The stacking fault may be removed by the motion of a partial dislocation across the loop. Furthermore, loops in general lie on close-packed planes.
Page 1 and 2: Analysis of the Extended Defects in
Page 3 and 4: My sincere thanks to the following
Page 5 and 6: OPSOMMING Hierdie dissertasie hande
Page 7 and 8: 4.2.5. Two-Beam Scattering Matrix 4
Page 9 and 10: Dedicated to my wife and parents
Page 11 and 12: SUMMARY The dissertation focuses on
Page 13 and 14: CONTENTS Chapter 1: INTRODUCTION 1
Page 15 and 16: 1 CHAPTER ONE INTRODUCTION Silicon
Page 17 and 18: 2.1. Introduction 3 CHAPTER TWO OVE
Page 19 and 20: 2.2.2 The Zinc-Blende Structure 5 T
Page 21 and 22: 2.3 Point Defects, Defect Migration
Page 23 and 24: v m Em vm0 exp( ) (2.2) kT 9 wher
Page 25 and 26: 11 explained and the concept of par
Page 27 and 28: 13 Straight dislocations furthermor
Page 29 and 30: 2.5 Partial Dislocations and Slip 1
Page 31 and 32: 17 Fig. 2.13. The geometrical setup
Page 33 and 34: 19 extrinsic stacking faults are th
Page 35: 2.8 Twinning 21 Twinning is a proce
Page 39 and 40: S n Td (3.2) 25 and is also referr
Page 41 and 42: 27 where a = a0(Z1 2/3 + Z2 2/3 ) -
Page 43 and 44: 29 Using this expression, curves of
Page 45 and 46: 31 As stated previously hard-sphere
Page 47 and 48: 33 where A is the atomic weight. Th
Page 49 and 50: 35 a vacancy dislocation loop if th
Page 51 and 52: 37 Fig. 4.1. (a) A wave incident on
Page 53 and 54: 39 Consider Fig. 4.2 which illustra
Page 55 and 56: 41 V0 is the mean inner potential o
Page 57 and 58: 43 beam left-hand side g' = 0 g' =
Page 59 and 60: 45 In addition another set of indep
Page 61 and 62: 47 When this is incorporated into t
Page 63 and 64: S ( s , z ) e T i Se ( / 0 )
Page 65 and 66: z0 z2 . xn cos and (4.47) D 1 proj
Page 67 and 68: 5.1 Introduction 53 CHAPTER FIVE LI
Page 69 and 70: 55 different orientations. The inte
Page 71 and 72: 57 Furthermore Pirouz et al. (1987)
Page 73 and 74: 59 intersection of the fault, the f
Page 75 and 76: 61 each nuclei because of the low s
Page 77 and 78: 63 (2000) found that subsequent ann
Page 79 and 80: 6.3.1 Ion Range and Defect Producti
Page 81 and 82: 67 Fig. 6.3. Total number of displa
Page 83 and 84: 7.1 Introduction 69 CHAPTER SEVEN R
Page 85 and 86: Fig. 7.2. Simulated diffraction pat
Page 87 and 88:
73 Fig. 7.3. A HRTEM image of the S
Page 89 and 90:
75 Fig. 7.5. The stacking fault sel
Page 91 and 92:
(Si/ni) 2 0.000018 0.000016 0.00001
Page 93 and 94:
79 may be concluded that the initia
Page 95 and 96:
81 Fig. 7.11. Bright field TEM micr
Page 97 and 98:
83 Fig. 7.12 which was obtained by
Page 99 and 100:
85 Fig. 7.13. Bright-field TEM micr
Page 101 and 102:
87 (a) (b) Fig. 7.15. The (a) exper
Page 103 and 104:
89 In the following paragraphs the
Page 105 and 106:
Fig. 7.18. CBED pattern taken of th
Page 107 and 108:
93 Table 7.5. The measured paramete
Page 109 and 110:
7.4.2 Results 95 Fig. 7.22. Bright-
Page 111 and 112:
97 Twin platelets on {111} planes
Page 113 and 114:
99 REFERENCES Blumenau, A.T., Jones
Page 115 and 116:
101 Hull, D., Bacon, D.J. : (1984)
Page 117:
103 Smith, D.J., Jepps, N.W. and Pa
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