Identification of new pillared-layered carbon nitride materials at high pressure

The compression of the layered carbon nitride C(6)N(9)H(3)·HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl(−) ions contained within C(12)N(12) voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl(−) ions out of the planes beginning above 10–20 GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer bonded phase. The transition pressure is calculated to be 47 GPa for the ideal structures. The new material has mixed sp(2)–sp(3) hybridization among the C and N atoms and it provides the first example of a pillared-layered carbon nitride material that combines the functional properties of the graphitic-like form with improved mechanical strength. Similar behavior is predicted to occur for Cl-free structures at lower pressures.