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matse exam 1 | 200 Questions Solved 100%Correct| Verified Answers
Aluminum has a face centered cubic (fcc) structure with an atomic radius of 0.143 nm and an
atomic weight of 26.98 g/mol. (a) Calculate the density of Al from this information. (b) What is
the planar density of atoms in the (110) plane.
A. (a) 1.35 g/L, (b) 6.11 atoms/nm^2
B. (a) 2.71 g/L, (b) 8.64 atoms/nm^2
C. (a) 0.678 g/L, (b) 8.64 atoms/nm^2
D. (a) 2.71 g/L, (b) 6.11 atoms/nm^2 - ✔✔B. (a) 2.71 g/L, (b) 8.64 atoms/nm^2
The density of niobium is 8.58g/cm3. It's atomic mass is 92.91 g/mol and its structure is bcc. (a)
Calculate the lattice parameter and the atomic radius from this information. (b) What is the
planar density of atoms in the (110) plane.
A. (a) a = 0.330 cm; R = 0.143 cm, (b) 26.0 atoms/nm^2
B. (a) a = 0.330 nm; R = 0.467 nm, (b) 13.0 atoms/nm^2
C. (a) a = 0.330 nm; R = 0.143 nm, (b) 13.0 atoms/nm^2
D. (a) a = 0.330 nm; R = 0.117 nm, (b) 26.0 atoms/nm^2 - ✔✔C. (a) a = 0.330 nm; R = 0.143
nm, (b) 13.0 atoms/nm^2
The first five peaks of the x-ray diffraction pattern for tungsten, which has a BCC crystal
structure; an x-ray source with a wavelength of 0.1542 nm was used.11. What are the indices
(hkl) for the first three peaks?
A. (110), (111), (200)
B. (111), (200), (220)
,C. (100), (110), (111)
D. (110), (200), (211) - ✔✔D. (110), (200), (211)
Long Range Order (LRO) - ✔✔refers to a repeating, or periodic, structure of atoms. When
LRO exists, the material has a crystalline structure where the building blocks are unit cells. all
metals
the first five peaks of the x-ray diffraction pattern for tungsten, which has a BCC crystal
structure; an x-ray source with a wavelength of 0.1542 nm was used.12. Determine the
interplanar spacings for the first two peaks
A. first peak = 0.228 nm; second peak = 0.159 nm
B. first peak = 0.1.59 nm; second peak = 0.228 nm
C. first peak = 0.121 nm; second peak = 0.091 nm
D. first peak = 0.091 nm; second peak = 0.121 nm - ✔✔A. first peak = 0.228 nm; second peak
= 0.159 nm
the first five peaks of the x-ray diffraction pattern for tungsten, which has a BCC crystal
structure; an x-ray source with a wavelength of 0.1542 nm was used.13. Determine the lattice
parameter
A. 0.228 nm
B. 0.322 nm
C. 0.159 nm
D. 0.121 nm - ✔✔B. 0.322 nm
Mixed SRO and LRO - ✔✔some solid substances have both amorphous and crystalline
regions. crystallinity in a normally amorphous material may impact the properties of the
material
,Crystal systems/structure - ✔✔There are 7 crystal systems used to completely fill 3-D space.
Have translational symmetry. Lattice constants and angles differentiate the systems.
List the 7 different crystal systems - ✔✔Cubic, tetragonal, orthorhombic, rhombohedral
(trigonal), hexagonal, monoclinic, triclinic
cubic system - ✔✔Axial lengths: a=b=c
Angles: alpha=beta=gamma=90 degrees
Tetragonal System - ✔✔Axial lengths: a=b does not equal c
Angles: alpha=beta=gamma=90 degrees
Orthorhombic System - ✔✔Axial lengths: a does not equal b does not equal c
Angles: alpha=beta=gamma=90 degrees
Rhombohedral (trigonal) system - ✔✔Axial lengths: a=b=c
Angles: alpha=beta=gamma does not equal 90 degrees
Hexagonal System - ✔✔Axial lengths: a=b does not equal c
Angles: alpha=beta= 90 degrees gamma=120 degrees
Monoclinic System - ✔✔Axial lengths: a does not equal b does not equal c
Angles: alpha=gamma= 90 degrees
beta does not equal 90 degrees
Triclinic system - ✔✔Axial system: a does not equal b does not equal c
Angles: alpha does not equal beta does not equal gamma does not equal 90 degrees
, Lattice constances - ✔✔the lengths of the sides of the unit; also referred to as lattice
parameters
Lattice angles - ✔✔angles between unit cell sides
the first five peaks of the x-ray diffraction pattern for tungsten, which has a BCC crystal
structure; an x-ray source with a wavelength of 0.1542 nm was used.14. Explain briefly why no
diffraction peak is observed for the (100) plane.
A. the (100) does not exist in tungsten
B. scattering from the (200) peaks destructively interferes with the (100) peak
C. the (100) does not exist in BCC
D. All of the above - ✔✔B. scattering from the (200) peaks destructively interferes with the
(100)
The seven ___crystal___ systems describe the ___shape__of the unit cell without considering
the atom positions.
True or False - ✔✔True
the lengths of the unit cell edges are referred to as the ___lattice parameters__.
True or False - ✔✔True
In hexagonal unit cells, the __(0010)__ plane is perpendicular to the c-axis.
True or False - ✔✔False
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