Peculiarities Of Phase Transformations In Graphite Intercalation Compounds With Bromine

The X-Ray (00L) and (HK0) patterns of third stage graphite intercalation compound with bromine have been experimentally investigated in the range of (150-290) K. The dependence of the intercalate identity parameter on temperature is determined. In the temperature range of (150-290) K there are three temperature intervals with different values of the linear thermal expansion coefficient (alpha):alpha(I) = (3.3 +/- 0.2) . 10(-5) K-1 in range I (238-300)K, alpha(II) = (2.8 +/- 0.2). 10(-5) K-1 in range II (174-238) K and alpha(III) = (2.4 +/- 0.2) . 10(-5) K-1 in range III (150-174) K. The abrupt change of the linear thermal expansion coefficient has been detected at 238 K and 174 K. The redistribution of the intensities of the (HK0) pattern main components on cooling from the 290 K to 150 K, in particular, a decrease of some maxima intensities indicates the active migration processes of bromine molecules in the two-dimensional lattice of the intercalate.