1. College of Materials Science and Engineering, Jilin University, Changchun 130012, China 2. State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China 3. College of Basic Science, Changchun University of Technology, Changchun 130012, China
In this work, high-pressure phase behavior of LiPN2 within 0–300 GPa was studied by using an unbiased structure searching method in combination with first-principles calculations. Three pressureinduced phase transitions were predicted, as tI16→hR4→cF64→oP8 at 44, 136, and 259 GPa, respectively. The six-fold coordination environments were found for all high-pressure polymorphs, which are substantially different from the four-fold coordination environments observed in the tI16 structure. The hR4 and cF64 structures consist of close-packed PN6 and LiN6 octahedra connected by edge-sharing, whereas the oP8 structure is built up from edge- and face-sharing PN6 and LiN6 octahedra with N lying in the center of the trigonal prisms. The electronic structure analysis reveals that LiPN2 is a semiconductor within the pressure range studied and P-N and Li-N bonds are covalent and ionic, respectively. The results obtained are expected to provide insight and guidance for future experiments on LiPN2 and other alkali metal nitridophosphates.
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