文摘
Considerable attention has been focused on developing a synthetic route to a carbon-nitrogen material withmechanical and thermal properties comparable or superior to those of diamond. To date, no substance withthe desired C3N4 stoichiometry in a silicon-nitride crystal lattice has been reported. One of the principaldifficulties in the pursuit of ultrahard carbon-nitrogen (CN) solids is the characterization of amorphous CNsamples. We describe a solid-state NMR study of a paracyanogen-like solid utilizing 13C-15N adiabatic-passageHartmann-Hahn cross-polarization (APHH-CP) to perform dipolar filtering and show that this method iswell-suited for recoupling 13C-15N in network solids. In addition, high-frequency electron paramagneticresonance (EPR) indicates a density of electron spins of approximately 1 × 1017 e-/cm3. We conclude bydiscussing how NMR and EPR data may be useful for optimizing CN-polymer samples as potential precursorsfor ultrahard carbon nitrogen solids.