Structure compatibility of graphite and phases formed from aluminum or magnesium phyllosilicates

Calcination of phyllosilicate/organics nanocomposites in inert atmosphere leads to in situ formation of graphitic carbon layers on silicate phases.Electrically conductive material (ceramics) is thus obtained.Despite an intensive research in this area, attention has not yet been paid to carbon/silicate interfaces in these systems.This study is focused on structure compatibility of graphitic carbon and the most abundant phases formed by transformation of aluminum phyllosilicates or magnesium phyllosilicates, i.e. cristobalite, mullite, forsterite, and protoenstatite.The aim is to find whether the phases can or cannot have a significant influence on the graphitic structure formation, and if the type of phyllosilicate (aluminum or magnesium) must be taken into account.Structure compatibility is determined by original method calculating the overlaps of atomic pairs carbon/another element.Carbon atoms lie in graphite(001) plane, atoms of another element lie in the given phase(hkl) plane.Different crystallographic planes of phases formed from the original phyllosilicates exhibit various structure compatibility with the graphite.The average number of overlaps of individual graphite(001)/phase(hkl) systems revealed the highest structure compatibility for mullite (M) followed by forsterite (F), protoenstatite (P) and cristobalite (C), namely M(102) > F(001) > P(100) > C(100).This sequence suggests that aluminum phyllosilicates, from which M is formed, could be a more suitable input component compared to magnesium phyllosilicates, from which F and P are formed.The lower number of overlaps for C compared to other phases indicates its small contribution to the overall structure compatibility.