D a t a were t aken over the temperature range o f 1

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Unformatted text preview: atures. P age - 50- 5 . 3 (a) SAMPLE A (quenched from 8 0 0 C ). - D SC T here were no detectable. transition peaks in the temperature region from 180 K to 4 4 0 K f or mole fractions of silver less than 0 . 1 ( x 0 . 1 ) . T his behaviour is consistent with the supposition of a dilute gas phase in which the silver atoms randomly occupy sites within the layer forming no definite structures. A s imilar behavior was observed in the X-ray studies done b y S choltz (63). T he calorimetric scans of the samples for which the silver mole fractions were in the range 0.1 < x < 0 .25 clearly indicate transitions occuring at T x = 0 . 1 5 and T = 2 7 2 2 2 K f or x = = 2 6 8 2 2 K f or 0 . 2 0 (Fig. 21a) with the peak height ( F i g . 21b) of the transition increasing with increasing mole fraction of silver ( x ) . T ransition peaks occurring at T = 2 8 8 2 2 K w ere found in all of the samples where the mole fraction of silver was greater than 0 . 2 0 . The transition temperature ( T 2 88 K ) = w as found to be independent of the silver concentration for 0 . 2 5 1 x < 0 . 5 (Fig. 2 1a) e ven though there was a double peak for some of the samples ( x > 0 . 2 5 s ee Fig. 2 1b). peak shape was observed in the graphite-Br C ulik e t . al. (36). 2 A s imilar system studied by The peak height of the transition was observed to increase with increasing silver mole fraction x i ndicating that the peak and associated transformation are associated with the intercalate. T h e results of the Page -50a- F igure 21a T ransition temperature ( T v ersus the silver mole c fraction ( X ) f or the order-disorder transition for h eating t he batch A ( quenched from 800 C ) s amples. ORDER-DISORDER TEMP T c MOLE FRACTION X in AgxTiS2 dH/dT vs T EMPERATURE F OR ( " KELVIN) TEMPERATURE AgxTiS2 R EFERENCE = PURE T iS2 SAMPLE S IZE = 2 3- 27 mg. HEATING RATE OK/minutc = 20 P a g e - 51- t emperature dependence v s . mole fraction of silver intercalate are summarized in P i g . 2 1 a . Ther...
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This note was uploaded on 10/08/2009 for the course CME MAT E 630 taught by Professor Dr. during the Fall '09 term at University of Alberta.

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