Ferroelectric ceramics for information storage and display
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LAND
The e l e c t r o o p t i c p r o p e r t i e s of h o t - p r e s s e d lead z i r c o n a t e t i t a n a t e c e r a m i c s and t h e i r a p p l i c a t i o n s a r e r e v i e w e d . C o a r s e - g r a i n e d , b i s m u t h - d o p e d c e r a m i c s with a v e r a g e g r a i n s i z e g r e a t e r than 2 ~m have light s c a t t e r i n g p r o p e r t i e s that can be v a r i e d by s w i t c h i n g the o r i e n t a t i o n of the f e r r o e l e c t r i c p o l a r i z a t i o n . F i n e - g r a i n e d b i s m u t h - o r l a n t h a n u m - d o p e d c e r a m i c s have a n effective b i r e f r i n g e n c e that can be v a r i e d e i t h e r by a p p l y i n g a n e x t e r n a l e l e c t r i c field ( c o n v e n t i o n a l e l e c t r o o p t i c effect) o r by p a r t i a l l y switching the r e m a n e n t p o l a r i z a t i o n ( e l e c t r o o p t i c m e m o r y effect). B a , Sn, or La m o d i f i c a t i o n s of the lead z i r c o n a t e t i t a n a t e s y s t e m p r o d u c e m a t e r i a l s with i m p r o v e d s w i t c h i n g c h a r a c t e r i s t i c s and e l e c t r o o p t i c effects s i m i l a r to t h o s e of f i n e - g r a i n e d b i s m u t h - o r l a n t h a n u m - d o p e d c e r a m i c s . L a n t h a n u m modified lead z i r c o n a t e t i t a n a t e ( P L Z T ) is s i g n i f i c a n t l y m o r e t r a n s p a r e n t than o t h e r e l e c t r o o p t i c c e r a m i c s . The P L Z T s y s t e m i n c l u d e s m a t e r i a l s with e l e c t r o o p t i e m e m o r y a n d e i t h e r l i n e a r o r q u a d r a t i c e l e c t r o o p t i e effects. The e l e c t r o o p t i c p r o p e r t i e s of modified lead z i r c o n a t e t i t a n a t e c e r a m i c s , e s p e c i a l l y P L Z T , c o m b i n e d with l o c a l i z e d s w i t c h i n g and m o d u l a t i o n c a p a b i l i t i e s a r e p a r t i c u l a r l y s u i t a b l e for i n f o r m a t i o n s t o r a g e and d i s p l a y d e v i c e s .
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r e c e n t l y , the light t r a n s m i s s i o n c h a r a c t e r i s t i c s of f e r r o e l e c t r i c c e r a m i c s w e r e so poor that t h e i r e l e c t r o o p t i c p r o p e r t i e s could not be i n v e s t i g a t e d . I m p r o v e d f a b r i c a t i o n m e t h o d s i n v o l v i n g h o t - p r e s s i n g 1-~ i n c r e a s e d the o p t i c a l t r a n s p a r e n c y of b i s m u t h - d o p e d *
s o l u t i o n s y s t e m s a r e d e s c r i b e d and d i s c u s s e d . T h o s e p r o p e r t i e s which a p p e a r to be e s p e c i a l l y u s e f u l for i n f o r m a t i o n s t o r a g e and d i s p l a y a p p l i c a t i o n s a r e e m p h a s i z ed.
The term "doped" refers to additionof lessthan 5 at. pct of the dopingelement;"modification"refersto additionof 5 at. pct. or moreof the modifying element(e.g., 5 to 30 at. pct. La).
POLING AND SWITCHING P R O P E R T I E S
lead z i r c o n a t e t i t a n a t e solid s o l u t i o n s to the extent that t h e i
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