Chp. 6: Crystal Structures

Question 1

AB

Answer 1

Hexagonal Close-Packed (HCP) hexagonal motifs

Question 2

ABC

Answer 2

Cubic Close-Packed (CCP) triangle motifs

Question 3

atomic packing factor of HCP and CCP

Answer 3

.74

Question 4

Slip planes for CCP

Answer 4

4 non-parallel slip planes, slide in 3 directions = 12 slip systems

Question 5

Slip planes for HCP

Answer 5

no close-packed planes, only 3 slip systems, not very ductile

Question 6

Body Centered Cube (BBC)

Answer 6

atoms on corners of cube but also one at center, rather than one at center of each face.

Question 7

Interstices

Answer 7

BBS crystals are divided into much smaller holes

Question 8

Slip planes for BBC

Answer 8

Same as CCP (12) equally ductile

Question 9

Face Centered Cubic (FCC)

Answer 9

arrangement of atoms, doesn’t describe if atoms are in contact
CPP always FCC
FCC not always CPP

Question 10

Close-Packed structure of silicon and diamond

Answer 10

FCC Crystal

Question 11

Graphite

Answer 11

ABABABAB
electrical conductor in planes
electrical insulator in perpendicular position
=anisotropic

Question 12

anisotropic

Answer 12

different properties in different directions

Question 13

Steric Hindrance

Answer 13

when chemical groups get in the way of others and prevent a neat arrangement