Ch. 3 Crystalline Structure Flashcards
Non crystalline =
amorphous
Optical properties of amorphous
transparent
Materials wiith cristals
Metals, ceramics, some polymers
Amorphous materials
Complex, rapid cooling, glasses
Plastics are
semi-crystalline
unit cell measurements
10^-9
Main unit cell types
SC, BCC, FCC, HCP
APF formula
(#atoms)(4/3)(pir^3)/a^3
FCC is similar to
hexagonal
Crystal density
p = (#atoms)(atomic weight)/((1 mol)(volume of cell))
Polyphormism meaning
Same element, different crystal structure
General material density heriarchy
metals > ceramics > polymers
7 types of crystal systems
Cubic, Hexagonal, Tetragonal, Rombohedral, Orthorhombic, Monoclinic, triclinic
Cubic crystal
Same distances, 90 degrees on all
Hexagonal
Triangular pattern
Tetragonal
2 same distances, 90 degrees on all
rombohedral
same distances, 3 same angles, not 90 degrees
orthorhombic
3 different measures, all 90 degrees
monoclinic
3 different distances, one angle not 90 degrees
triclinic
all are different
Position in lattice example
[123]
Plane example in lattice
(123)
Linear density
atoms/length
Planar density
atoms centered/area of plane
Anisotropic properties
depend on crystal direcion
Examples of anisotropic properties
Stifness, Conductivity, Refraction
Isotropic properties
dont depend on crystal direction
Braggs law
n lambda = 2d(hkl)sin(theta)
D(hkl) formula
D(hkl) = a/sqrt(h^2+k^2+l^2)