1 5 t hen increase to 1 2 1 a f or the stage 2 c

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Unformatted text preview: 1 c ompounds are somewhat unstable at room temperature and that the mole fraction limits ( 0 . 2 5 < x < 0 . 3 5 ) o f the stage 1 - s tage 2 r egion may be a function of the cooling rate in preparing the thermally intercalated samples. average separation of T i S 2 It appears that the maximum 0 l ayers is ~ 6 . It a nd that the i ntercalation of silver for x > 0 .35 i ncreases the free energy of the crystal causing the pure stage 1 i ntercalation phase to be unstable at room temperature and "eventually decay (and possibly de-intercalate) to the more stable stage 2 s tructure ( 0 . 1 5 < x < 0 .25). A s ummary of the stage and P age - 31l attice parameters vs silver atom concentration is shown in Fig. 15a and F i g . 1 5 b . T he x-ray diffraction results from the thermally intercalated sa'mples which were quench cooled from 1 0 0 0 C a gree very well with results obtained from the electro-intercalated and thermally intercalated samples used by Scholtz ( 31) a nd Gerards e t . al. (65). 3-4 X -RAYS GROUP C ( annealed from 1 0 0 0 C - g roup 2 ) A n ew group of Ag T iS2 s amples (group C ) 0 < x x s 0.5 w as prepared in order to investigate the differences in the X-ray diffraction patterns between the Ag T iX x 2 s amples which w ere quench cooled from 8 0 0 C ( forming predominantly stage 2 compounds) and samples quench cooled from 1 0 0 0 C ( forming both stage 1 a nd stage 2 c ompounds). The group C s amples were prepared using the same procedure as the previous two groups except that they were intercalated at 1 0 0 0 C a nd cooled over a period of 1 0 h ours instead of being quench cooled. X-ray and XRF analysis was then done on each of the slowly cooled (Group C) Ag T iS2 s amples. The X-ray X d iffraction patterns for these samples were similar to the patterns from the pure T i S 3.406 0 to 3 . 4 0 8 2 0 . 0 0 2 < x I 0.5. 2 h aving lattice parameters a a nd c = 5 .690 to 5 . 7 0 8 2 0 . 0 0 4 T here were also weak T i 0 2 a = f or X -ray diffraction lines present which were used as a calibration check on the equipment but suprisingly no pure silver lines appeared in Page -32- t he diffraction p a...
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