Experiment-Driven Modeling of Crystalline Phosphorus Nitride P3N5: Wide-Ranging Implications from a Unique Structure

Nitridophosphates have emerged as advanced materials due to their structural variability and broad technical applicability. Their binary parent compound P3N5, a polymeric network of corner- and edge-sharing PN4 tetrahedra with N[2] and N[3] sites, is a particularly interesting example. We present a study of the band gap and electronic structure of α-P3N5 by using soft X-ray spectroscopy measurements and DFT calculations. The band gap, which is crucial for all applications, is measured to be 5.87±0.20 eV. This agrees well with the calculated, indirect band gap of 5.21 eV. The density of states are found to show dramatic variation between the nonequivalent N sites and a high degree of covalency. Coupled to these results is what is, to our knowledge, the largest core hole shift reported to date for a soft X-ray absorption spectrum. We propose an intuitive bonding scheme for α-P3N5 that explains the observed band gap and unique density of states, while providing a framework for predicting these properties in known and yet to be discovered PN compounds. We briefly consider the implications of these results for new low-dimensional P and PN materials, which alongside graphene, could become important materials for nanoelectronics.