Behavior of the liquid silver electrode in a solid-oxide electrolyte concentration cell
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i m p o r t a n t c o n s e q u e n c e o f the d e v e l o p m e n t of s o l i d o x i d e e l e c t r o l y t e s h a s b e e n t h e in situ d e t e r m i n a t i o n of the o x y g e n a c t i v i t y i n l i q u i d m e t a l s . E l e c t r o m o t i v e f o r c e m e a s u r e m e n t s on o x y g e n c o n c e n t r a t i o n c e l l s h a v e b e e n u s e d f o r t h i s p u r p o s e on a wide v a r i e t y of l i q u i d m e t a l s and alloys. 1 In particular, r e s u l t s have been r e p o r t e d for l i q u i d silver.2's T h e p r e s e n tp a p e r d e s c r i b e s t h e b e h a v i o r of the l i q u i d s i l v e r e l e c t r o d e u n d e r c u r r e n t f l o w a n d i n t r o d u c e s an a l t e r n a t e t e c h n i q u e - - a v o l tammetr ic or ' 'polarographic- like ' ' technique dependent upon the electrochemical removal of oxygen from the liquid metal at the metal-electrolyte interface. EXPERIMENTAL T h e e l e c t r o l y t e w a s a n i m p e r v i o u s t u b e o f Z r O e + 10 m o l e p c t C a O , c l o s e d f l a t a t one e n d . T h e o u t e r s u r f a c e of t h e c l o s e d e n d w a s p l a t i n i z e d by a p p l y i n g d r o p s of a 5 t o 10 p c t c h l o r o p l a t i n i c a c i d s o l u t i o n w h i c h w a s subs e q u e n t l y d e c o m p o s e d a t 600 ° t o 7 0 0 ° C . The cell d e s i g n used in t h i s i n v e s t i g a t i o n is shown in F i g . 1 . T h e e l e c t r o l y t e t u b e w a s 24 in. l o n g w i t h a n o m i n a l I D o f ~ in. a n d O D o f ~ in. E n o u g h 9 9 . 9 9 9 + p c t A g w a s i n s e r t e d i n t o t h e t u b e (3.8 g ) t o m a k e t h e l i q u i d ~ in. i n h e i g h t . A T-m.~ " alumina rod, w h i c h h a d two - ~ - i n . h o l e s a n d w a s t a p e r e d a t one e n d , w a s p o s i t i o n e d ~ i n . a b o v e the i n s i d e b o t t o m s u r f a c e o f the e l e c t r o l y t e . T h e j o i n t b e t w e e n t h e C h r o m e l A l e a d w i r e a n d t h e 0 . 0 2 0 in. P t w i r e w a s i n t h e hot z o n e so t h a t c o r r e c t i o n s f o r thermoelectric f o r c e s were unnecessary. T o p r e v e n t the p l a t i n u m w i r e f r o m b e i n g a t t a c k e d by s i l v e r v a p o r , the C h r o m e l A w i r e w a s g r o u n d t o f i t t i g h t l y i n s i d e the a l u m i n a r o d . T h e o x y g e n c o n c e n t r a t i o n i n the s i l v e r w a s c o n t r o l l e d by b u b b l i n g A r - O 2 m i x t u r e s o f k n o w n compositions through the m e t a l . This s e r v e d t o stir the l i q u i d a n d k e e p the bulk c o n c e n t r a t i o n c o n s t a n t d u r i n g the p a s s a g e of c u r r e n t . T h e a l u m i n a t u b e w a s 18 in. l o n g w i t h a n ID of ~ in. a n d O D of 1 i n . A p i e c e of 0 . 0 1 8 - i n . t h i c k p l a t i n u m T. H. ETSELL, formerly Graduate Student, Department of Metallurgy and Materials Science, University of T o r o n t o , T o r o n t o , Ontario, Canada, is now a National Research Council of Canada Postdoctoral Fe
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