CHAPTER 4 :
IMPERFECTIONS IN SOLIDS
→
Imperfections presence influenced
properties of materials .
Point defects
→ Localised disruptions perfect atomic or ionic structure
arrangements crystal
pÉ%É)
in in a
> adding atoms
Intentionally
→ Cause I> Unintentionally adding atoms
-
"
→
produce during said ;fi cation as of local disturbance, ↓ /Mᵈ
314J
a result
, ,
@
z@srxi
8704Mt oB1aiomy.q
created by atomic rearrangements in an existing crystal , g.
µ @
R
i.
e
vacancies
62¥ eV / atomk "
"
→
A
vacancy is
produced when an atom or an ion is
missing from its normal she in the
crystal structure .
g.
I
,M
!!!!! ?!?!? gµ
3ʳᵈ
"
→ Produced during solidification → atomic
arrangement g.
pi4 east
i.
38×10
of }
no .
Energy required
atoms cm /
* 62
↓ g.
(%-)
,
Nv = n exp
↓ ↓
Temperature NO Of Energy required
of vacancies Gas constant for the formation
-
no -
Kelvin
defe% ✗
in
per cmˢ y.qgy-cai.no ,-1kt of a vacancy
^¥=e×p(i¥-)
,
314J MOI K-1
'
= 8-
_
-
Absolute Temperature ,
K
Boltzmann Constant
Total no -
of =
1-38×10-23 J / atom K
atomic sites
=
8-62×10-5 ev /atom K
Interstitial
→ An atom occupy an interstitial site between
surrounding atoms in normal atom sites .
→ Self -
interstitial produces large distortions -
⊕
if %
Schottky imperfection -
2 oppositely charged ions are missing from an ionic crystal to create a cation -
anion di
vacancy .
→
Points defects in ionic
crystal Frenkel imperfection -
G) cation moves into an interstitial site in an ionic
crystal ,
cation
vacancy is created .
Impurities
→
Alloying is used in metals to improve mechanical strength and corrosion resistance
→ Solid solution is when added to the host material the and no new are formed
solute are maintained , structures
-
atoms , crystal structure is
added
Interstitial small atoms to host atom
-
→
In solid solution
↳ Substitutionat
sameha%Fms
,
-
added to host atom .
?⃝
IMPERFECTIONS IN SOLIDS
→
Imperfections presence influenced
properties of materials .
Point defects
→ Localised disruptions perfect atomic or ionic structure
arrangements crystal
pÉ%É)
in in a
> adding atoms
Intentionally
→ Cause I> Unintentionally adding atoms
-
"
→
produce during said ;fi cation as of local disturbance, ↓ /Mᵈ
314J
a result
, ,
@
z@srxi
8704Mt oB1aiomy.q
created by atomic rearrangements in an existing crystal , g.
µ @
R
i.
e
vacancies
62¥ eV / atomk "
"
→
A
vacancy is
produced when an atom or an ion is
missing from its normal she in the
crystal structure .
g.
I
,M
!!!!! ?!?!? gµ
3ʳᵈ
"
→ Produced during solidification → atomic
arrangement g.
pi4 east
i.
38×10
of }
no .
Energy required
atoms cm /
* 62
↓ g.
(%-)
,
Nv = n exp
↓ ↓
Temperature NO Of Energy required
of vacancies Gas constant for the formation
-
no -
Kelvin
defe% ✗
in
per cmˢ y.qgy-cai.no ,-1kt of a vacancy
^¥=e×p(i¥-)
,
314J MOI K-1
'
= 8-
_
-
Absolute Temperature ,
K
Boltzmann Constant
Total no -
of =
1-38×10-23 J / atom K
atomic sites
=
8-62×10-5 ev /atom K
Interstitial
→ An atom occupy an interstitial site between
surrounding atoms in normal atom sites .
→ Self -
interstitial produces large distortions -
⊕
if %
Schottky imperfection -
2 oppositely charged ions are missing from an ionic crystal to create a cation -
anion di
vacancy .
→
Points defects in ionic
crystal Frenkel imperfection -
G) cation moves into an interstitial site in an ionic
crystal ,
cation
vacancy is created .
Impurities
→
Alloying is used in metals to improve mechanical strength and corrosion resistance
→ Solid solution is when added to the host material the and no new are formed
solute are maintained , structures
-
atoms , crystal structure is
added
Interstitial small atoms to host atom
-
→
In solid solution
↳ Substitutionat
sameha%Fms
,
-
added to host atom .
?⃝
