Nanocomposites and nanomaterials

Peculiarities of Phase Transformations in Graphite Intercalation Compounds with Non-polar Intercalates
Mandrolko V.M.1, Borovoy M.O.1, Ovsiienko I.V.1, Len T.A.1, 
Matzui L.Yu. 1, Gomon O.O.1, Naumova D.D.2  
Taras Shevchenko National University of Kyiv, Department of Physics1 and Chemistry2, 64/13 Volodymyrska st., 01601, Kyiv, Ukraine
E-mail: mandrolko.v@gmail.com
In presented work the peculiarities of phase transformations in the layers of non-polar intercalates in intercalated compounds based on fine crystalline graphite are considered. As it is known, for non-polar intercalates in graphite intercalation compounds (GICs) there are several phase transformations. These transformations in the intercalates layers, in contrast to polar intercalates, are not only from the “quasiliquid” to “quasicrystalline” state, but they also are related with the structural realignment of the intercalates layers from one to another commensurate or noncomensurate to graphite layer lattice. For non-polar intercalates such transitions may also be accompanied by a change in the accommodation coefficient, that is, the amount of additional charge transmitted from the intercalates molecules to the graphite layers.
In presented work phase transformations in GICs have been investigated by XRD method. Figure presents the temperature dependence of identity parameter Is for third stage GIC with bromine. To determine dependence Is(T) the position of reflex (008) from the intercalates layers in the intervals of diffraction (FeKa1,2) angles (2)=66.0071.00 been recorded. 
 
Figure. Is(T) for third stage GIC with bromine, .	As can be seen from the Figure, there are three intervals in the dependence Is(T), which differ in the angle of inclination to the temperature axis. The existence of temperature intervals I, II and III with different values of the linear thermal expansion coefficient indicates that at temperatures ~175 K and 250 K there is a structural  rearrangement of the intercalates layers. This rearrangement is accompanied by changes in the interaction of bromine atoms with the nearest graphite layers.