Pressure-induced novel phases of YN4 as a possible high energy density material

Transition metal nitrogen-rich compounds are novel high-energy-density material compounds, characterized by superior stability and high energy content. Incorporating yttrium into pure polymeric nitrogen materials can induce the formation of new polymeric nitrogen compounds under high pressure. Here, a structural search of YN4 was conducted in the pressure range of 0–100 GPa using the CALYPSO crystal structure prediction method combined with first-principles calculations. Three stable phases P41212, P1¯(I) and P1¯(II) were obtained, and the phase transition sequence of YN4 is P41212 → P1¯(Ⅰ) → P1¯(Ⅱ) under high pressure. The calculations results indicate that the P41212 phase and P1¯(I) phase are metallic. In contrast, the P1¯(II) phase is semiconductor with an indirect bandgap. Moreover, the energy densities of the P41212 phase, P1¯(I) phase and P1¯(II) phase are comparable to those of FeN4. These excellent performance characteristics indicate that YN4 has a broad application prospect in the field of energetic materials and explosives.