I i s tacking sequences o rdering of the intercalate

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: temperatures and enthalpy changes of intralayer intercalate order-disorder transitions in Br intercalated graphite using differential 2 s canning calorimetric techniques. superlattice in Ag T iS x 2 Evidence of the silver c ompounds has been observed i ndirectly by Suter ( 23) u sing X-rays and Leonelli ( 37) u sing R aman s pectroscopy and directly by Unger e t . al. ( 21) w ith electron diffraction. P a g e - 21T he silver atoms intercalated in T iS 2 c rystals were found to form a n ordered triangular superlattice with a lattice parameter of d 3 a . 0 T he stacking sequence was a ssumed to be abc in accord with the findings of S cholz ( 31) and L eonelli ( 37). Subsequently the X-ray measurements of Suter e t . a l . ( 2 3 ) on A go.33 T iS2 r evealed the same J3a d3a 0 0 x i ntralayer ordering with an abab . . . s tacking sequence. 2 -4 Sample Preparation and Specifications A gxTiS2 s amples were prepared thermally by heating the appropriate amounts of silver powder a nd T iS evacuated quartz ampoule. p owder in an 2 The silver powder was obtained from Materials Research C orporation.and t he T iS prepared as specified in section 2-2. 2 p owder was Samples of Ag T iS2 X i n the range 0 < x < 0 . 7 w ere prepared by mixing appropriate weight quantities of the silver and T i S 2 p owders (total weight for each sample = 0 . 5 g m.). The mixture was placed in quartz ampoules (typically 1 cm. 0 . D x 7 -12 cm. long) and evacuated ( < l o - * t orr) while heating the ampoule (to 150 C ) wi-th h eating tape to remove excess oxygen adsorbed on the walls of the ampoule ( i n order to prevent the possible formation of T i 0 ) . 2 T he sealed ampoules were then shaken using an assortment of vibrators to obtain a homogeneous mixture of silver and T iS ampoule. 2 p owder in the P age - 2 2 - T wo groups of samples were prepared and labelled group A a nd group B . T he ampoules were then uniformly heated to 800 C a nd 1 0 0 0 C ( for group A a nd group B s amples respectively) for a period of 4 - 8 d ays. The samples were cooled once during the 4 - 8 d ay intercalation period to roo...
View Full Document

Ask a homework question - tutors are online