33 t is2 s ample grown by vapour transport this work

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Unformatted text preview: rimetry experiments carried out on thermally intercalated Ag T iS p owders are x 2 p resented. The experiments were carried out on samples with nominal intercalate concentrations 0 < x < 0 .6 a nd for temperatures between 100 K a nd 600 K . thesis reviews the properties of T iS the preparation of the T i S p rocess. 2 2 C hapter 2 of this c rystals and describes p owders and the intercalation Chapter 3 describes the X-ray diffraction and. X-ray fluorescence techniques that were used as diagnostic tools in sample characterization. Chapter 4 r eviews the Differential Scanning Calorimetry techniques. Chapter 5 p resents the results of the calorimetry measurements. These measurements did not reveal any hysteresis in the transition, a result b P age - 7 - t hat is in agreement with the previous assertions of the second-order nature of the transition. specific heat near T C The variation of the is thus obtained from the measurements and the results are compared to theoretical predictions obtained by S chick and Walker ( 52) w ho used renormalization group methods for atoms adsorbed on a substrate. This dicussion of the results is contained in Chapt.er 6 a long with the conclusions arising from this work. P age - 8C HAPTER 2 S AMPLE P REPARATION 2 -1 T ransition Metal Dichalcogenides T i S 2 i s a member of the family o f t ransition metal dichalcogenide (MX ) c ompounds that exist as layered 2 s tructure crystals consisting of combinations of a transition metal ( M ) f rom Groups I V , V o r V I o f the periodic table with a c halcogen (X) chosen from the elements S , S e , T e and T a . The layers consist of planes of transition metal atoms (M) sandwiched between two hexagonally packed planes of chalcogenide atoms ( X), ( Fig. 1 ) T he six-fold coordination of the chalcogenide atoms around the transition metal atoms occurs primarily in either a trigonal anti-prism ( IT) c onfiguration ( F i g . 2 ) o r a trigonal prism (2H) configuration (Fig. 3). T he structure of these materials results in their physic...
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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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