Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
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expla<strong>in</strong>ed and <strong>the</strong> concept <strong>of</strong> partial dislocations and slip discussed s<strong>in</strong>ce it is<br />
important <strong>in</strong> <strong>the</strong> understand<strong>in</strong>g <strong>of</strong> <strong>the</strong> formation <strong>of</strong> stack<strong>in</strong>g faults.<br />
2.4.2. The Dislocation L<strong>in</strong>e and Burgers Vector<br />
To understand <strong>the</strong> concept <strong>of</strong> <strong>the</strong> dislocation l<strong>in</strong>e and Burgers vector <strong>the</strong> follow<strong>in</strong>g<br />
geometrical analogy may be followed and is shown <strong>in</strong> Fig. 2.7. Imag<strong>in</strong>e a dislocation<br />
be<strong>in</strong>g produced by mak<strong>in</strong>g a cut <strong>in</strong> a perfect crystal. Follow<strong>in</strong>g this <strong>the</strong> two sides <strong>of</strong><br />
<strong>the</strong> crystal are shifted with respect to one ano<strong>the</strong>r by a translation vector <strong>of</strong> <strong>the</strong> lattice.<br />
Then <strong>the</strong> miss<strong>in</strong>g material is added or surplus material removed. The shifted surface<br />
<strong>of</strong> <strong>the</strong> cut may grow toge<strong>the</strong>r <strong>in</strong> such a way that <strong>the</strong> cut is no longer discernable. Thus<br />
at <strong>the</strong> <strong>in</strong>side <strong>of</strong> <strong>the</strong> crystal, at <strong>the</strong> edge <strong>of</strong> <strong>the</strong> former cut surface, a l<strong>in</strong>e <strong>of</strong> strongly<br />
disturbed material rema<strong>in</strong>s. This l<strong>in</strong>e is called <strong>the</strong> “dislocation l<strong>in</strong>e”.<br />
(a) (b)<br />
(c)<br />
Fig 2.7. The geometrical analogy <strong>of</strong> a Volterra-cut describ<strong>in</strong>g a dislocation present<br />
<strong>in</strong> a crystal (from Bollmann (1970)). (a) A cut is made <strong>in</strong> a perfect crystal. (b) The two<br />
sides <strong>of</strong> <strong>the</strong> crystal are shifted with respect to one ano<strong>the</strong>r by a translation vector <strong>of</strong><br />
<strong>the</strong> lattice. (c) The shifted surface <strong>of</strong> <strong>the</strong> cut may grow toge<strong>the</strong>r <strong>in</strong> such a way that <strong>the</strong><br />
cut is no longer discernable.