The a b s e n c e o f d i e l e c t r i c d i v e r g e n c e i n i m p r o p e r f e r r o e l e c t r i c s makes i t p o s s i b l e t o o b t a i n a h i g h p y r o e l e c t r i c f i g u r e of m e r i t n e a r their t r a n s ition t e m p e r a t u r e . R e s u l t s o f m e a s u r e m e n t s c a r r i e d o u t a s a f u n c t i o n o f t e m p e r a t u r e on r e p r e s e n t a t i v e s o f three c l a s s e s o f i m p r o p e r ferroelect r i c s : r a r e -e a r t h m o l y b d a t e s , p r o p i o n a t e s , and b o r a c i t e s , show t h a t i n e a c h o f these the f i g u r e o f merit rises t o a p e a k v a l u e w h i c h i s s u p e r i o r t o t h a t of t r i g l y c i n e s u l f a t e . A n a l y s i s ofthe e x p e r i m e n t a l r e s u l t s u s i n g a Landau t y p e f r e e -e n e r g y model y i e l d s a n e s t i m a t e of the optimum f i g u r e o f m e r i t o b t a i n a b l e .

Thin films of LaF 1 deposited on Si or GaAs substrates have been observed to form blocking contacts with very high capacitances. This results in comparatively-hysteresisfree and sharp C-V (capacitance-voltage) characteristics for MIS structures. Such structures have been used to study the interface states of GaAs with increased resolution and to construct improved photocapacitive infrared detectors.