Solid State Flashcards
Summarise the solid state of crystals
- arranged periodically
- sub unit can be used to recreate full structure
- both short and long range order
Summarise the solid state of amorphous materials
- short range order only
- no unique sub unit can generate the whole structure
Define lattice
- infinite array of points where each point has identical surroundings
Define Unit Cell
- a building block
- when repeated in all directions it gives the lattice
Summarise lattice counting rules
- 1/number of cells shared with
- e.g. shared with 8 cells? counts as 1/8th when counting for one cell
What’s a lattice coordination number?
- the number of nearest neighbours to each ATOM
State coordination numbers for
i) simple primitive unit cell
ii) body centred cell
iii) face centred cell
i) 6
ii) 8
iii) 12
What must you always draw when representing miller planes?
- an axis!!!
- a comes towards you, b to the right, c straight up!
How’s a miller index denoted and what do they stand for?
(h k l)
h = divisions on a axis
k = divisions on b axis
l = divisions on c axis
Describe the miller plane for (230)
- 2 divisions on a axis (crosses at a/2 = 1/2)
- 3 divisions on b axis (b/3 = 1/3)
State Bragg’s Equation
nλ = 2d sin θ
Summarise stacking
- stacking refers to how layers of atoms are stacked onto one another
- how are the gaps filled?
Summarise HCP stacking
- hexagonal close packed
- coord 12
- ABA style (mirror plane in B)
Summarise CCP
- cubic closepacked
- coord 12
- ABC style packing
- rotational symmetry around “B” plane
Compare packing efficiency of HCP & CCP to BCC
- HCP CCP efficiency of circa 74% (very close)
- BCC (body centered cubic, simple cubic) circa 68%
