Unformatted text preview: concentrations ( x ) i n the range 0 . 2 5 5 x 1 0 . 5 .
A s imilar behavior w a s observed in t h e graphite-Br s ystem studied by Culik e t . a l . ( 36). 2 T h e peak height of the transition was observed to increase with increasing mole
fraction x i ndicating that the peak and associated
transformation a r e due to t h e intercalate. T h e d ouble peak observed in the calorimetric studies of
the Group A ( quenched f r o m 800 C ) s a m p l e s w as n ot evident in
the data taken o f the G r o u p B s amples (quenched from 1 0 0 0 C ).
T h e results of the temperature dependence v s . mole fraction
o f silver intercalate are summarized in F i g . 2 2 . O nce again ( a s f o r the Group A s a m p l e s quench cooled from 8 0 0 C ) t here
was no detectable hysteresis in t he t ransition temperature . P age - 52a- F igure 22 dH/dT v ersus temperature for different silver mole f r a c t i o n X from batch B ( quenched from 1000 C ) s amples. dH v s T emperature
dT -x = heating r ate = T emperature ( K) P a g e - 53T = 2 88 K b etween heating and cooling scans and the baseline behavior was consistent w i t h that expected for a s econd order
transition. 5 -4 ( b ) S AMPLE B ( quenched from 1 0 0 0 C ). - L O W T EMPERATURE Low temperature ( 1 8 0 K < T < 2 60 K ) c alorimetric data of
the G r n u p B A gXTiS2 s a m p l e s were similar to the low
temperature data from the Group A samples. The scans where O < x 5 0 . 3 w ere devoid o f a ny features that could b e
a ssociated with a transition while scans for samples with
silver mole fraction ~ ~ 0 . s howed a reproducible
transition at T = 2 0 8 2 2 K. T h e program used for the lower temperature scans is outlined in Appendix 1 1 . C ooling curves were not obtainable due to the poor cooling efficiency and
sensitivity of the equipment. T h e peak height of the transition was found to increase with increasing mole
fraction of silver intercalate indicating that the transition
is associated with the silver intercalate in the s a m p l e s . 5 -4 ( c ) L ow T e m p X-ray...
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- Fall '09
- Diffraction, Sulfur, Intercalation, lattice parameters