Observation of Molecular and Polymeric Nitrogen-Filled NaCl Layers

Abstract

While pristine NaCl is chemically inert in N2-rich environments, this study reports the formation of a novel NaCl(N2)2 hybrid salt at pressures above 50 GPa. First-principles simulations and synchrotron X-ray diffraction analysis revealed that NaCl and N2 react to produce an N-filled salt in which N2 molecules break the isotropic NaCl structure into two-dimensional layers. In contrast to the insulating properties of wide-band gap NaCl, NaCl(N2)2 exhibits a narrow electronic band gap of 3.3 eV, becoming an indirect semiconductor. Further compression to 130 GPa induces the polymerization of N atoms into zigzag N chains. These findings demonstrate the emergence of unusual N bonding under extreme conditions, offering a feasible approach for designing layered NaCl frameworks to modulate nitrogen polymerization.