# Chapter 12: Structure and Properties of Ceramics¶

### Example 12.1 Page no 418¶

In [5]:
a=30

import math
ratio=(1-math.cos(a*math.pi/180.0))/math.cos(a*math.pi/180.0)

print"Cation to anion raio is ",round(ratio,3)

Cation to anion raio is  0.155


### Example 12.2 Page no 423¶

In [16]:
r_Fe=0.077  # in nm Radius of iron cation Fe++
r_O=0.140  #in nm  Radius of Oxygen anion O--

ratio=r_Fe/r_O

print"Ratio is ",ratio
if 0.414<ratio<0.732:
print"Co-ordinaton no. is 6"
print"Structure is Rock Salt type"
else:
print "Coordination no is not 6"


Ratio is  0.55
Co-ordinaton no. is 6
Structure is Rock Salt type


### Example 12.3 Page no 424¶

In [18]:
A_Na=22.99         # in g/mol
A_Cl=35.45          #in g/mol
r_Na=0.102*10**-7  #in cm Radius of Na+ ion
r_Cl=0.181*10**-7  #in cm Radius of Cl- ion

a=2*(r_Na+r_Cl)
V=a**3
n=4                 #For FCC, no. of atoms are 4 per crystal
density=n*(A_Na+A_Cl)/(V*Na)

print"Density is ",round(density,2),"gm/cm**3"

Density is  2.14 gm/cm**3


### Example 12.4 Page no 436¶

In [26]:
Na=6.023*10**23   #Avogadro number
density=1.955     #in g/cm**3
A_K=39.1          #in g/mol
A_Cl=35.45        #in g/mol

import math
N=Na*density*10**6/(A_K+A_Cl)
Qs=2.6           # in eV
k=8.62*10**-5    # in eV/K  Boltzmann Constant
T=500.0+273.0        # in K
Ns=N*math.exp(-Qs/(2*k*T))

print"No. of Schottky Defects are ",round(Ns,-17),"/m**3"

No. of Schottky Defects are  5.31e+19 /m**3

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