I

n, c.,
'', fiIst

o p s .  L
' .  I n d .
t ) .
, .  S e r . ,

I  n n d
D r o p

3 5 , 2 4 1

M . S c .

( 2 0 0 4 ) ,

t 5 ,  I  I ,

"Drop

a w - l l i l l

IIGPTi r a q i  J o u r n a l  o f  C h e m i c a l  a n d  p e i r o l e u m  E n g  n e e r i n gV o l . 8  N o . 1  ( M a r c h  2 0 0 7 ) 4 3 - 4 S
E f f e c t  o J  S i n t e r i n g  T e m p e r a t u r e  a n d  S o a k i n g  T i m e  o n  t h e  p h y s i c a l

and Dielectric Properties of BaTiO3 for Different BaiTi Ratios

A m e l  S .  M e r z a ' a n d  K h a l i d  F .  C h a s i b t '

,. 
' 

M;nb.r) at Scj. ? aaa I e. haotog - hoq
(  i  n i . a !  L 4 * R e ' i , C  D e p  |  ! t 4 t 4 !  l n i v e t s , D o t t e ( h a o t a g - h a q

Abstract

...::,i::.i,:l:1,,! 
*'*::''hcr kc ihip,o\Lnent afphrsicat dnd.tietectric prope ies afBariot cercnic nlate,itrt by

:,.,:::., ii,!,:.':, ,i! 
,,*,".,r,.o, a. Bacot. rh. p,eparcd *nptes sinterect at .lifferent tenperanws a,d yalyths sodkrjg

!t::n:.,1,!c,tc'.,t,: \h.aw,th, ihcrtn.\tns t.he \i:tletih8 tetnpetuturc ||hhin t35aac and soakins ti"rc af to nri gi"" !,"ui
;nttrtcot dnd physicat ptopctlL.s, wh(h indt.dte !he rcactiok is conplete at higher renperalure ana parrca.

J(ulralrft: sintering,soaking, bariunr tiranate.

Introduction
Piezoelectficity is one property ofa group ofdielectrjc

matciais called feroelectrics. These marc ars are
cfiaracterizcd by a domain strucrure that can bc nrodified
by an electric field. The piezoelectric efiect nranjfests as
a sponlaneous potential difference across the opposite
fac€s of a volume of nraterial when under an applied
stfess. This potential is proportional directly to the
mechanical stress applied to it. The inverse is also true,
i . e . ,  a p p l i c a t i o n  o f  a n  e l e c t f i c  f i e l d  c a u s e s  s r r a r n  r n  a
v o l u r n e  o f  p i e z o c l e c t r i c  m a t e r i a l  I  I  L'l 

he fiN! piczoelectric nraiciial discovcred was
C . r l c i u I r  f i r : i r ) . u c .  w I i c h  f " ,  r t . e  p e r o r . k i r e  s r - u ( r L r c  ^
u J d i l i o r . - i  L o n r t | e r c r a l  e \ r r r p l e  i s  E d r . u r l  r i u n i t e .  w h i - , 1
rs comnro ly used in capacitors and lransducefs due ro its
high pennittivity 12l. The reacrion behveen BaCO3 and
TiO, proceeds via several internrediate staces of which
f o  n a l i o n  o f  B a T i O !  h  t h e  n r o s t  d i s t i n c r .  T h e  g . u , n  , , , "
o f  B a t i o r  c c r J r n  c  j s  ( o r r t o l l c d  b y  h  b i r : o n  t h e  g r " i n
g r 0 $ t t r  b y  r  I n g  . i  c \ L L r (  ! .  r o r . .  o .  l j O  . h  a  , c c o n d
p h a s e  w h i c h  b e h a v e s  a s  i n h i b i l o r  [ 3 ] .  T t r e  s t o i c h i o m e t r i c
powdeG can be oblaincd by adjusting the Ba/Ti ratio,
where dre higher AtTi ratio leads lo the irrcorporation of
excess Bariunr in rhe powdcr [4]. It is extecled rhat
o p t i m u n ]  s i n i c f i n g  b e h a v i o r  a n d  e t e c t r i c  p r o p e f i i e s  a r e
o b t a i n e d ,  w i t h  s t o i c h i o m e t r y  r a n g e  0 . 9 9 j  -  i . 0 0 J j l .

Experimental work
The piezoceramic mare al bariLrm riranlte (BaTiOj)

was lrepared by the r€action of a suitable grade of
BaCO3 with TiO,. These raw marerials are weighed out
i n  J o , r r  d r l f e r e n r  r a t : o s  '  1 . 0 3  t .  I  l .  I  1 . 0 J .  I  t . 0 0 l l
r c c o r d i n g  i o  t h e  s t o i c h o m e t r i c  e q L r c l i o n  b e l o w :

BaCO3 + TiO? -,) BaTiOr + CO? (l)

Fof each run the raw materials mixed and lnilted in an
agate ball mill for 8 hrs and rhen calcined rne resutr
powder at I200oC for 8 h.s.

T h e  c a l c i n e d  p o w d e r  m i l l e d  a n d  s i e v e d  i n  a n  3 8  L - n r
< i e r e .  r f e r r  w e i g h e d  a  p r o p e r  a n o u | l t  - 1 d  p r e \ ,  i t  i n L l
n ' x j r g  q : h  P V A  b i n d e r ,  i  c  r o d  w i r h  I  c r n  J j a m e r e r
us'ng 2.5 ion load. These samples thcn sintered in air at
differcnt temperatures (1200, I300, 1350.C) ior differen!
p e r j o d s  ( 2 , , 1 , 6 , 8 ,  I 0  h f s ) .  T h e  b u l k  d e n s i r y  n e a s u r e d
and the trLre porosity is calcLrlated by dre relarioh.

,,,,, - ,,,,,1 aY'"* I el
t,tpteS4area Dta : .4F':/ r. drra\\J

S : r (  e  r \ e  d e n . i t ]  o l  w a l e r  e q u d l  l o  I  g  .  m  .  r t  e r .
r  , , ,

r.r"" -lt !!!!!! !! rc. (JJ
L true.tehsity l

I J C P E  V o l . 8  N o . 1  ( M a r c h  2 0 0 7 ) 4 3



EJJ,ct afsnikting letrDetuhtrc an.l soaki|1g l't! an thephrsicat 
ahd dictechic pt'openies afBaTntfat aiJ|Uent BdTirdtias

The trLre density for BaTiOr is 6 02 g cn!3 l5l and the

rclative dielectric constant (K) may be measuled by usrng

LCR eter for the elecnoded samplesl

( 3 )

f i :  l d L l \ d c ' ]  i b  o i n  i O  l r . ] p l e ' ) i n r ' r e J r l

differcnt te pemtufcs with Ba/Ti 
= 0 997

: ; ; 6

r i g . I  r c  c e n r a g  r r J e  p o f o  i r )  o f B d l i o - a m " l c
. , n L i r r d  , r  d i " f e r e r r  r e n  p e r a L J f e ' w  r r  B i  I I  

n  a o '

I  i a  J  B J l l  d c n s i l )  o f  B  r T r o r  s  r m p l c a  s i  l c r e d  a t

d  f i e r c n t  t e n l p e f r l u r e s  w i l h  B a ' T i  
=  l  0 l

t  i g .  d  P e r c e n r a g e  I - u e  D o  o s i r )  o i  B "  ,  i o r  s a n p  e q

, l r r - r c r e d  a r  d i f r e i e ' r |  r e n  p e r a r ' r r c s  $ i r h  B a n  i  
=  l  0 l

I

t
IWh€re c is the capacitance of the prepared samples 

(in

f r r i d J ,  d  i  I r i . l r e '  o f  l l . c  s r m p l e  ' i n  n \ '  c o  i '  l l c

n . i i i ' i ' i  '  ' , )  o r  '  * * ' "  
-  8  8 5 '  l 0 '  1 2  C : n -  n l  o r d  A  i '

ihe cross-sectional area of sanrples (nt

Results and Discussion

Bulk density
Results shows that $e sinlering tenrpcraturc and soakjng

timc has a remarkable influence on the bulk d€Dsity of the

DreDared BaTiOr for the two Ba,iTi ratio's as sho$n in Fig'

i. and rie. 3. Above 1300"c sintering caL$es dhcontinuous

er"i,' noi'1h ly i.rcrea"ed drftsior in L|e liqJid 
phrse A

i . r . , u " :  o f  o ' t i . r " , L  c o - r p o L ' r d '  a r e  p o , s i b l e  $ : r ' \  c i L h e r

exccss of TiOr or BaCOr' Under the condition oi excess

r i L a r . . - . .  a  l i a  r ' d  r \ d ' e  i c  f o r r n c d  r o  e  r h  t r r c e  ' i n l c r i n b  r r r d  l h i s

t r . . .  u c e r .  r c p o r r i a  e x p c '  
' m e n r " l D  i r  r i s  l  ' n d  f r g  l  [ J ]

I ' '

i
!  . "

:
\

3
I

.t :

t

!

Fis. 5 Dielectric constant (measLrred at l0 KHz) as a

funition soaking tinre for BaTior with BaiTi= 0 99?

True pofosity

Porositv for the siniere'l BaTiOr with 
different

s : n L e r i n c i . n o e r o r u r e  a n d  , o a l ' i n g  l i m e  f o r  l h e  n \ o  c a r e (

o f  B a  I  i  r O  o o r ,  l . 0 l l  $ d "  . d l c l - l - e d  i r  l h e  p e r c e r t a g e

hJ;t;c'-i;; i;"'6 or Barior (6.02 gn/cm3l and
plotted in Fig. 2 and Fig 4

I J C P E  V o l . B  N o  1  ( M a r c h  2 0 0 7 )



AthelS. Mer.a and Khalid F. Chdsib

mples
=  1 . 0 3

I

-r-l
: _

. l

l r )  
" . ;= 0.991

' . - . ' . - ' - -

References
L Hsiao-Lin, Wang "Structure and Dielectric properties

ofPerovskile Barium Titanare" December 04, 2002.
2.Theodore, M. H., Jules, M., & Roberl, J.L., J. Am.

C € r a m .  S o c . , 4 9  [ 6 ]  2 9 5  ( 1 9 6 6 ) .
3 . P a s c a l ,  P . ,  C h r i s t i a n ,  C . ,  A n n e ,  L . ,  &

A m .  C e r a m .  S o c . ,  8 2  u  l l ,  ( 1 9 9 9 ) .
4 . M y u n g ,  c .  K . ,  D o h ,  Y . K . ,  & N o n g ,

Ceram. Soc. 83 [2] December (2000).
5 . l l l a v a c  J . ,  " T h e  T e c h n o l o g y  o f  c l a s s  a n d  C c f a n i c s ' ,

E l s e v i e r  S c i e n t i f i  c  P L r b l  j s h i n g  C o m p a n y ,  ( 1 9 8 3 ) .

I

B e r n a r d ,  T . .  J .

M . H . ,  J . A m .

Fig 6 Dielectric constaDt (measured at l0 KHz) as a
irnclion soaking time for BaTi03 with BtTi = 1.03

trrelectric constant
Dielectric constant of BaTior is extremely sensitive to

3aTi ratio, sintering temperature, and soaking period as
i : o w n  i n  F i g .  5  a n d  F i g . 6 ,  i n  w h i c h  t h e  d i e l e c r r i c
ionslant irrcreased as the sintering temperarure increased,
:: reaches a maximum value at l350oc at 8-10 hrs, and it
:iff€rs slighlly afler this remperature.

Conclusions
: - S i n l e r i n g  b e l o w  1 3 5 0 . C  i s  a d v i s e d  t o  p r e v e n t

production of reaction phases. However, high
temperature is rcquired to inrprove tbe sintered density
b y  t h e r m a l a c t i v a t i o n .

2.The physical and dielectric properties influence by ihe
BtTiratio, sintering temperature and the soaking time.

i.Increasing TiO: in a small proportion effect Iargely the
p l y s i c a l  a n d  d i e l e c r r i c  D r o p e r t i e s  o f r h e  r c s u h e d  p i e c e .

.l.lncreasing BaCOj in a quantity larger rhan that ofTiO,
also effect dr€ physical and dielectric propedies of
BaTiO3. But the small addition of TiO? effect is more
e f f e c t i v e  r h a n  t h a r  o f  l a r g e r  a m o  n t  o f B a C O r .

different

perc€ntage
L/cm') and

I J C P E  V o l . B  N o . 1  ( M a f c h  2 0 0 7 )