MTL 200 2025 EXAM QUESTIONS
AND 100% CORRECT ANSWERS!!
What is the relationship between the unit cell edge length and the atomic radius for HCP
crystal structures?
a = 2R
How many atoms are in the HCP structure?
6 atoms
What is the formula for volume of HCP unit cell in terms of a and c?
V = (3ca^2sqrt(3))/2
What are the coordination numbers of FCC, BCC, and HCP structures?
FCC: 12
BCC: 8
HCP: 12
What are the APF of FCC, BCC, and HCP structures?
FCC: 0.74 or 74%
BCC: 0.68 or 68%
HCP: 0.74 or 74%
What is the formula for the volume of 4 atoms in FCC?
V=4*(4/3)(piR^3)
What is polymorphism? What is it called for elements?
- the phenomenon of a solid material existing in more than one form of crystal structure.
- for elements, it is called allotropy
,What coordinate form do you use for crystallographic directions for cubic structures,
hexagonal structures and for a family of equivalent directions?
Cubic structures: [UVW]
Hexagonal structures: [uvtw]
Family of equivalent directions: <uvw> <uvtw>
How do you convert [UVW] to [uvtw]?
u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
What is the formula for linear density (LD)?
LD = (# of atoms centered on a direction vector)/(length of direction vector)
What kind of brackets are used for linear? ( ) or [ ]?
[]
What is the formula for planar density? (PD)
PD = (# of atoms centered on a plane)/(area of a plane)
What kind of brackets are used for planar? ( ) or [ ]?
()
What is anisotropy?
material properties are DEPENDENT on orientation
What is isotropic?
material properties are INDEPENDENT of specimen orientation
Given the crystal structure, what are the reflections present (RP)?
BCC
, FCC
Simple Cubic
RP
BCC: (h+k+l) even
FCC: h, k & l are all even or all odd
Simple Cubic: All
What are 3 examples of elements with an FCC structure?
Al, Ag, Au
What are 3 examples of elements with a BCC structure?
Cr, Fe, Tungsten
What are 5 examples of elements with an HCP structure?
Cd, Zn, Mg, Ti, Cu
What are 1 example of elements with a Simple Cubic structure?
Polonium
What is the Bragg's Law formula? What does each variable represent?
nλ = 2dsinθ
n = order of reflections
λ = wavelength of the x-ray beam
d = interatomic spacing
θ = incident angle of the x-ray beam
If given a diffraction angle of 40 degrees, what value do you use in the Bragg's
Law equation?
20 degrees (diffraction angle/2)
What is the sufficient condition for diffraction to occur?
AND 100% CORRECT ANSWERS!!
What is the relationship between the unit cell edge length and the atomic radius for HCP
crystal structures?
a = 2R
How many atoms are in the HCP structure?
6 atoms
What is the formula for volume of HCP unit cell in terms of a and c?
V = (3ca^2sqrt(3))/2
What are the coordination numbers of FCC, BCC, and HCP structures?
FCC: 12
BCC: 8
HCP: 12
What are the APF of FCC, BCC, and HCP structures?
FCC: 0.74 or 74%
BCC: 0.68 or 68%
HCP: 0.74 or 74%
What is the formula for the volume of 4 atoms in FCC?
V=4*(4/3)(piR^3)
What is polymorphism? What is it called for elements?
- the phenomenon of a solid material existing in more than one form of crystal structure.
- for elements, it is called allotropy
,What coordinate form do you use for crystallographic directions for cubic structures,
hexagonal structures and for a family of equivalent directions?
Cubic structures: [UVW]
Hexagonal structures: [uvtw]
Family of equivalent directions: <uvw> <uvtw>
How do you convert [UVW] to [uvtw]?
u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
What is the formula for linear density (LD)?
LD = (# of atoms centered on a direction vector)/(length of direction vector)
What kind of brackets are used for linear? ( ) or [ ]?
[]
What is the formula for planar density? (PD)
PD = (# of atoms centered on a plane)/(area of a plane)
What kind of brackets are used for planar? ( ) or [ ]?
()
What is anisotropy?
material properties are DEPENDENT on orientation
What is isotropic?
material properties are INDEPENDENT of specimen orientation
Given the crystal structure, what are the reflections present (RP)?
BCC
, FCC
Simple Cubic
RP
BCC: (h+k+l) even
FCC: h, k & l are all even or all odd
Simple Cubic: All
What are 3 examples of elements with an FCC structure?
Al, Ag, Au
What are 3 examples of elements with a BCC structure?
Cr, Fe, Tungsten
What are 5 examples of elements with an HCP structure?
Cd, Zn, Mg, Ti, Cu
What are 1 example of elements with a Simple Cubic structure?
Polonium
What is the Bragg's Law formula? What does each variable represent?
nλ = 2dsinθ
n = order of reflections
λ = wavelength of the x-ray beam
d = interatomic spacing
θ = incident angle of the x-ray beam
If given a diffraction angle of 40 degrees, what value do you use in the Bragg's
Law equation?
20 degrees (diffraction angle/2)
What is the sufficient condition for diffraction to occur?
