1. Crystal Structure and Crystallography 재료구조론
Prof. Ki-Bum, Kim
2013. Spring
Hi, my name is kiju kim. Todays’ subject is mainly about basic of graphene and new equipment to improve quality of graphene

2. We start with Periodic Table of the Elements
HEX
BCC
(BCC)
FCC
(FCC)
CUB
DIA
TET
ORC
MCL
RHL SC

3. Scaling down of Materials

4. Importance of Chemical Bonding of Atoms
► Ionic bonding
► Covalent bonding
► Metallic bonding
(strong but no directional)
(strong and directional)
(strong and no directional)

5. Metallic Structure: Closed Packing of AtomsB

6. Closed Packed Structures: FCC and HCPB C
Stacking sequence
ABCABCABCABC (FCC)
ABABABABABAB (HCP)
APF  74 %

7. Stacking Sequence of FCC (ABCABCABC….)

8. Stacking Sequence of HCP (ABABAB……)

9. HCP versus FCC
FCC
HCP
Note the difference between stacking sequence and unit cell definition
HCP – basal plane (closed packed plane)
FCC – (111) plane (closed packed plane)

10. Unit Cell of HCP (Hexagonal Close-Packed Structure)Y A B c
Materials : Mg, Ti, Co, Zn, Zr, …..
Note that c/a = 1.633

11. Unit Cell of FCC (Face-Centered Cubic)X Z Y a
A plane
B plane
C plane
Materials : Ni, Cu, Pd, Ag, Au, Pt, …..

12. Another Common Type of Metal Structure: BCC
APF  68 %
Intrinsically unfilled structure
Bonding Directionality
High E, Tm (?)
Mostly transition metal
Materials : Cr, Fe, Nb, Mo, Ta, W, …..
Coordination Number: 8

13. Revisit Crystal Structure of FCC – (110) Plane Projection
[111]
[001]
[110]
{111} Planes A B C
 Stacking sequence of FCC: A B C A B C A B C …..

14. Dislocation Structure in FCC: Shockley Partial Dislocation
Perfect Dislocation in FCC: a/2 [110]
Shockly Partial Dislocation
 a/6 [112] type !
a/2[112]
a/2[110]
a/6[112]

15. Shockly Partial Dislocation:
Moving atom from B → C position A B C
Burgers vector: a/6[112]

16. Shockly Partial Dislocation:
A B C A B C A B C A
A B C A C A B C A B
Stacking fault (one layer missing)
→ intrinsic stacking fault
Locally HCP form
A B C A C B C A B C
Intrinsic stacking fault
Extrinsic stacking fault ▼ A

17. Shockly Partial Dislocation:B C
B→C
C→A
A→B
[111]
[110] projection

18. Twin Structure Formation:

19. Twin Structure Formation:

20. Grain Boundary Structure:

21. Grain Boundary Structure: CSL

22. Grain Boundary Structure: CSL
Shown is the calculated (0oK) energy for symmetric tilt boundaries in Al produced by rotating around a <100> axis (left) or a <110> axis (right). We see that the energies are lower, indeed, in low S orientations, but that it is hard to assign precise numbers or trends. Identical S values with different energies correspond to identical grain orientation relationships, but different habit planes of the grain boundary.

23. Defect Structure in Colloidal Particle Self-AssemblyV I D G

24. Interstitial Sites (Interstices):
Geometry
Coordination #
Cation-Anion radius ration 2 3 4 5 6
<

25. Interstitial Sites in FCC:
Octahedral sites ; 4
Tetrahedral sites ; 8
What are the position of each sites and how many sites in an unit cell ?

26. Interstitial Sites in HCP:
Tetrahedral sites ; 4
What are the position of each sites and how many sites in an unit cell ?

27. Interstitial Sites in HCP:
Octahedral sites ; 2
What are the position of each sites and how many sites in an unit cell ?

28. Interstitial Sites in BCC:
3 octa octa = octa
What are the position of each sites and how many sites in an unit cell ?

29. Interstitial Sites in BCC:
r+ri
4/2 tetra x 6 = 12 tetra
What are the position of each sites and how many sites in an unit cell ?

30. Interstitial Sites in BCC:
Octahedral sites ;
Tetrahedral sites ;
FCC
BCC
Octa (0.414)
Tetra (0.225)
6 (0.155, 0.63) (0.29)