The heat capacities and heat content of molten cerium by levitation calorimetry
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H298.15 =
-0.01255
T2 +
75.305 T - 32,995.401 J / m o l .
The c o r r e l a t i o n c o e f f i c i e n t for the c u r v e fitting p r o c e s s was 0.81. The data b e t w e e n 1700 K and 2500 K i n d i c a t e d a l i n e a r heat content function as d e s c r i b e d by the equation: H T --H298.15 = {31.616 4- 0.596}(T - 1077) + {38,917.267 4- 575.049} J / m o l .
The a v e r a g e p e r c e n t d e v i a t i o n b e t w e e n this and the e x p e r i m e n t a l v a l u e s was 0.67. E x p e r i m e n t a l heat contents w e r e c o r r e c t e d for Convection and r a d i a t i o n heat l o s s e s d u r i n g the fall of the s a m p l e f r o m the l e v i t a t i o n c h a m b e r into the c a l o r i m e t e r . The m a x i m u m e s t i m a t e d e r r o r for the l e v i t a t i o n c a l o r i m e t r y work was 4-2.5 pct. L IQUID m e t a l high t e m p e r a t u r e t h e r m o d y n a m i c data a r e often not a v a i l a b l e and cannot be e s t i m a t e d f r o m p r e s e n t t h e o r i e s of liquids. At p r e s e n t , l e v i t a t i o n drop c a l o r i m e t r y technique o f f e r s the only p r e c i s e m e a n s of m e a s u r i n g the t h e r m o d y n a m i c p r o p e r t i e s Of liquid m e t a l s to as high as 1000 d e g r e e s above t h e i r m e l t i n g points. 1-3 I m p r o v e d m o d e l s to d e s c r i b e liquid m e t a l s s t r u c t u r e s could be developed as m o r e precise thermodynamic information becomes available. The l e v i t a t i o n c a l o r i m e t r y technique e s s e n t i a l l y c o n s i s t s of s i m u l t a n e o u s l y l e v i t a t i n g and h e a t i n g a conductive m e t a l s a m p l e in a n o n u n i f o r m , a l t e r n a t ing, e l e c t r o m a g n e t i c field b e f o r e b e i n g dropped into a c o n v e n t i o n a l drop c a l o r i m e t e r . Specific types of l e v i t a t i o n c o i l s a r e needed to p r o v i d e the v e h i c l e for floating the m e t a l s a m p l e . The eddy C u r r e n t s e s tablished within the s a m p l e e n a b l e the s a m p l e to be supported without the aid of a c o n t a i n e r if the v e r t i c a l component of the field is equal to o r g r e a t e r than the weight of the s a m p l e . As d e s c r i b e d by J e n k i n s et al, 4 the force on the s a m p l e d e p e n d s on the field s t r e n g t h and g r a d i e n t . S t a b i l i z a t i o n of the s a m p l e o c c u r s by p l a c e m e n t of a u n i f o r m opposing f o r c e a g a i n s t the s a m ple. T h e s e r e s t r a i n t s force the liquid s a m p l e to the p o s i t i o n of m i n i m u m field s t r e n g t h . The s a m p l e t e m p e r a t u r e d e p e n d s upon the p o s i t i o n of the s a m p l e in the field, the r a t e of heat l o s s , the shape of the coil, the power to the coil and weight of the s a m p l e . The r a t e of s a m p l e heat l o s s was r e g u l a t e d by the a r g o n h e l i u m p u r g e gas c o m p o s i t i o n . A Copperblock c a l o r i m e t e r s y s t
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