7 Z 4, pp. 746∼751
PLZT-x/(100-y)/y : g à k Ä8 ý P ê s ¥ ¹ Å- mP ê s ¥ ¹ Å V ê s ¹ ÅT
ø ¶ B Ú
Å Ò §¹ ¢ ¤ @ / < Æ § õ < Æ §¹ ¢ ¤ õ , Å Ò 660-756
L |( å , Û o
Â
Ò â @ / < Æ § Ó ü t o < Æõ , Â Òí ß 608-737
(2010¸ 2 Z 4 1{ 9 ~ Ã Î6 £ §, 2010¸ 5 Z 4 24{ 9 Ã º& ñ : r ~ Ã Î6 £ §, 2010¸ 7 Z 4 13{ 9 > F S X & ñ )
: r ½ ¨\ " f H PLZT-x/100-y/y (x = 2, 6, 8; y = 5) [ j b ` ¦ ¦^ - ¦^ ì ø Í6 £ xZ O Ü ¼ Ð ½ + Ë$ í # ª
| 9
_ [ j b ` ¦ ] j ¸ % i . y ª ` ¦ ¦& ñ ¦, x (La) ª _ 7 £ x \ É r PLZT-x/95/5 [ j b _ l & h
$ í
| 9 õ © s & ³ © ` ¦ ¸ % i . PLZT-x/95/5[ j b _ y © Ä » - ì ø Íy © Ä » © s & ³ © ` ¦ · ú Ð l
0 A # 4 ¤ è Ä » Ö ¦ 8 £ ¤& ñ , P (Polarization) - E (Electric field) s § 4 / B G 8 £ ¤& ñ ` ¦ % i . PLZT- 2/95/5 [ j b _ â Ä º ì ø Íy © Ä » © - y © Ä » © s H $ : r © s : r ¸ T
L= 126
◦C, y © Ä » © \
"
f © Ä » © s H ¦ : r © s : r ¸ T
U= 210
◦C Ð ' a ¹ 1 Ï÷ &% 3 . PLZT-6/95/5ü < PLZT-8/95/5 [
j b _ â Ä º T
U¿ º > h_ T
U 1õ T
U 2_ : r ¸ Ð z ¤Ü ¼ 9, PLZT-8/95/5 [ j b \ " f H T
Ls
t · ú § ¤ . 7 £ ¤, PLZT-6/95/5 [ j b _ â Ä º $ : r _ © s : r ¸ T
L= 89
◦C, T
U 1= 196
◦C Õ
ªo ¦ T
U 2= 214
◦C % i Ü ¼ 9 PLZT-8/95/5 [ j b _ â Ä º ¦ : r _ © s : r ¸ T
U 1= 174
◦C, T
U 2= 227
◦C % i . P-E s § 4 / B G 8 £ ¤& ñ õ ÐÂ Ò' PLZT-x/95/5 [ j b _ © [ þ t s T
Ls _ : r ¸% ò % i
\
" f H ì ø Íy © Ä » : £ ¤$ í s × æ s § 4 / B G s z ¤Ü ¼ 9, T
L∼ T
Uü < T
L∼ T
U 1s : r ¸% ò % i \ " f H y
© Ä » : £ ¤$ í é ß { 9 s § 4 / B G s z ¤ . : r ½ ¨_ z ´+ « > õ ÐÂ Ò' PLZT-x/95/5 & ñ _ > h ) a + þ
AI _ © ¸\ ¦ ] jî ß % i .
Ù þ
d # Q: y © Ä » ^ , ì ø Íy © Ä » ^ , © s , PZT, PLZT
Ferro-antiferroelectric Phase Transitions in PLZT-x/(100-y)/y Ceramics
Jong-Ho Park ∗
Department of Science Education, Chinju National University of Education, Jinju 660-756
Byung Chun Choi
Department of Physcis, Pukyong National University, Busan 608-737 (Received 1 February, 2010 : revised 24 May, 2010 : accepted 13 July, 2010)
Ferro-antiferroelectric ceramics of PLZT-x/100-y/y (x = 2, 6, 8; y = 5) were synthesized using a solid-solid reaction. The effects of La doping on the ferro-antiferroelectric phase transitions were studied by using complex dielectric constant and P-E hysteresis loop measurements. The antiferro- electric phase transition temperature T
Lappeared at 126
◦C in the PLZT-2/95/5 ceramic and at 89
◦C in PLZT-6/95/5 ceramic. In the PLZT-8/95/5 ceramic, we could not detect an antiferroelec- tric peak related to a phase transition at temperatures above room temperature. The ferroelectric phase transition temperature T
Uappeared at 210
◦C in PLZT-2/95/5 ceramic, but ferroelectric
-746-
temperatures near T
Uwere observed at T
U 1= 196
◦C and T
U 2= 214
◦C in PLZT-6/95/5 and at T
U 1= 174
◦C and T
U 2= 227
◦C in PLZT-8/95/5 ceramics. Here, T
U 1and T
U 2correspond to ferroelectric and multi-cell-cubic (MCC) transition temperatures, respectively. Capacitors mode of PLZT-2/95/5 and PLZT-8/95/5 ceramics were characterized by a well-saturated P-E hysteresis loop. However, the shape of the P-E hysteresis loop changed with increasing La contents. The results of the investigations are summarized in a phase diagram for PLZT-x/95/5 ceramics.
PACS numbers: 77.22.-d, 77.22.Gm, 73.20.-I
Keywords: Ferroelectric, Antiferroelectric, Phase transition, PZT, PLZT
I. " e  ] Ø
þ
j H y © Ä » ^ Ó ü t| 9 Ð" f ` ÐÚ ÔÛ ¼ s à Ô+ þ A & ñ ½ ¨ ¸
\
¦ ° ú H BaTiO 3 , PbTiO 3 (PT), Pb(Zr,Ti)O 3 [PZT], (Pb,La)(Zr,Ti)O 3 [PLZT] & ñ õ 8 £ x © ½ ¨ ¸\ ¦ ° ú H SrBi 2 Nb 2 O 9 , SrBi 2 Ta 2 O 9 & ñ 1 p x É r ì ø Í ¸^ B j ¸o è _
@ /^ Ó ü t| 9 Ð" f B j ¸o í ß \ O ì r _ 6 £ x6 x$ í M :ë H \ ´ ú §
É
r ' a d ` ¦ = å J ¦ e . s [ þ t y © Ä » ^ Ó ü t| 9 [ þ t É r Z } É r Ä » Ö
¦` ¦ כ ¹½ ¨ HDRAM (dynamic random access memory) B
j ¸o è ü < ï ß À Óì rF G (Remanent polarization, P r )` ¦ s
6 x ô Ç q 6 fµ 1 Ï$ í l % 3 è (Nonvolatile ferroelectric ran- dom access memory; NVFRAM) _ z ´6 x 0 p x$ í s B Ä º ß
¼l M :ë H \ < Æë H& h , í ß \ O & h 8 £ ¤ \ " f F g# 3 0 A > ½ ¨
÷ & ¦ e . : £ ¤ y , y © Ä » ^ _ ï ß À Óì rF G` ¦ s 6 x ô Ç FRAM
è H B Ä º É r ì rF G ì ø Í 5 Å q ¸\ ¦ t 9 " é ¶ s é ß
÷
&# Q ¸ l % 3 ? /6 x` ¦ Ä »t ½ + É Ã º e H q 6 fµ 1 Ï$ í l % 3 è
Ð 6 x s 0 p x . s : £ ¤$ í M :ë H \ ´ ú § É r ½ ¨ [ þ t s
RF-sputtering, Pulsed laser deposition (PLD), metal- organic chemical vapor deposition (MOCVD), Õ ªo ¦ Sol-GelZ O 1 p x _ # Q ~ ½ ÓZ O Ü ¼ Ð ~ Ã Ì} ` ¦ ] j ¸ # Ó ü t o & h :
£ ¤$ í ` ¦ ½ ¨ ¦ e [1–16].
ô
Ǽ # , y © Ä » ^ Ó ü t| 9 × æ ` ÐÚ ÔÛ ¼ s à Ô & ñ ½ ¨ ¸\ ¦
° ú
H & ñ É r ABO 3 _ o < Æd ` ¦ t ¦ e Ü ¼ 9, # l " f A H H s : r ì ø Í â ` ¦ t ¦ e H ª s : r s ¦ B H É r s
: r ì ø Í â ` ¦ t ¦ e H ª s : r s 9 O H 6 £ § s : r í ß ès
. @ /Â Òì r _ ` ÐÚ ÔÛ ¼ s à Ô & ñ ½ ¨ ¸\ ¦ t H y © Ä »
^
H A 2+ B 4+ O 2− 3 ¢ ¸ H A 1+ B 5+ O 2− 3 _ d Ü ¼ Ð ½ ¨$ í ÷ &# Q e
. s Ó ü t| 9 × æ \ " f PZTü < PLZT & ñ É r Pb/La ü <
Zr/Ti _ ¸$ í q \ ª ô Ç ½ ¨ ¸ © s & ³ © s ' a ¹ 1 Ï
÷
&# Q ´ ú § É r ½ ¨ \ _ K ½ ¨÷ &% 3 . PZT & ñ _ â Ä
º Zr/Ti_ ¸$ í q \ Curie : r ¸ (T C ) s © { 9 M :
H © Ä » $ í ` ¦ ? / 9, T C s { 9 M : H ª s : r õ 6 £ § s
: r _ × æd s ² ú 4 R µ 1 Ïì rF G (Spontaneous Polariza- tion, P S )` ¦ t 9 y © Ä » $ í ¢ ¸ H ì ø Íy © Ä » $ í ` ¦ · p
∗