In this essay, I will talk about something about the material of Military body armor,
Nomex is the mean material of the body armor.
In order to bulletproof demand, the material should
have high elasticity and hardness. Bulletproof fiber
has been to the di
1.
Solution:
The formula is
QV
N v =Nexp
kT
Because of the data is the vacancies of unit volume Ag, so for V=1m3
V N A 9.5 g/cm 3 1 106 cm 3 6.02210 23
N= Ag
=
A Ag
107.9 g /mol
28
5.3 10
Transform the formula
( )
Nv
QV
=exp
N
kT
Nv
Q
= V
So
N
kT
ln
(
1.
Show that the minimum cation-to-anion radius ratio for a coordination number of
6 is 0.414. [Hint: use the NaCl crystal structure, and assume that anions and
cations are just touching along cube edges and across the face diagonals.]
Solution:
This figu
The accompanying figure shows a unit cell for a hypothetical metal.
(a) To which crystal system does this unit cell belong?
(b) What would this crystal structure be called?
(c) Calculate the density of the material, given that its atomic weight is 145
g/m
1. (a) Using the ionic radii data in your textbook, calculate the coulombic force of
attraction between Na+ and Cl- in NaCl. You may want to check the structure of
NaCl to figure out the separation distance between the ions.
(b) What is the repulsive forc
1.
Please describe in your own understanding what the crystal structure is. You are
expected to describe in both Chinese and English. Your description should be
from two directions as I discussed in class. One is from Space Lattice to Crystal
Structure, w
Metallic Crystal Structures
1.
For the HCP crystal structure, show that the ideal c/a ratio is 1.633.
A
A
B
C
B
C
Solution:
In the HCP crystal structure, I choose A for the center atom. There are 12 atoms surround the A
with the same distance. Choose the
1. Calculate the number of atoms contained in a cylinder 1 m in
diameter by 1 m deep of (a) magnesium and (b) lead.
Solution
(a) After check the table on book, I know the density of magnesium is 1.74g/cm3,
its equal to 1.74 1012 g /m 3 . The volume of the
1. Chemical analysis in materials science laboratories is frequently
done by means of the scanning electron microscope. In this
instrument, an electron beam generates characteristic x-rays that
can be used to identify chemical elements. This instrument
sa