Theoretical Tracing of a Novel Route from Molecular Precursors through Polymers to Dense, Hard C3N4 Solids

We investigate theoretically a novel experimental polymer route to C 3 N 4 materials. Starting with simple molecules, we follow the initial steps of oligomerization of several carbodiimide based C 3 N 4 precursors. A sequence of hypothetical models with a chemically resonable structure for the resulting low-density C 3 N 4 polymers is constructed. Simulating high pressures, we show that one hypothetical polymer structure might undergo a polymorphic transition into cubic C 3 N 4 . Another one is transformed into a novel dense 3/4-connected C 3 N 4 structure with odd-membered rings and C−C and N−N bonds.