Author Affiliations
1School of Physics and Electronic Information, Yantai University, Yantai 264005, People’s Republic of China2Beijing Computational Science Research Center, Beijing 100193, People’s Republic of China3School of Physics and Electronic Engineering, Linyi University, Linyi 276005, People’s Republic of China4Shandong Key Laboratory of Optical Communication Science and Technology, School of Physical Science and Information Technology, Liaocheng University, Liaocheng 252059, People’s Republic of Chinashow less
Fig. 1. Enthalpy difference of BeN4 relative to the P4/nmm structure under high pressure. P1-BeN4 and P21/c- BeN4 are previously known high-pressure structures from Ref. 29. The phase transition pressures are indicated by the arrows.
Fig. 2. Crystal structure of the stable P4/nmm-BeN4 at ambient pressure: (a) side view along c axis; (b) a axis. The green spheres are Be atoms and the gray spheres N atoms.
Fig. 3. Phonon dispersions and phonon density of states (PHDOS) of P4/nmm-BeN4 at ambient pressure.
Fig. 4. Molecular dynamics simulations and radial distribution function of P4/nmm-BeN4. (a) and (b) Equilibrium structures at 10 ps and fluctuations of the total potential energies during the AIMD simulation at temperatures of 300 and 500 K, respectively. (c) RDF for N–N separations.
Fig. 5. Electronic properties of P4/nmm-BeN4 at ambient pressure. (a) Band structure. (b) PDOS of Be and N atoms. (c) COHP between N and N atoms.
Fig. 6. SSAdNDP-derived chemical bonding pattern of P4/nmm-BeN4 at ambient pressure: (a) 4 × 2c-2e Be–N σ bonds, ON = 1.65|e|, iso-value = 0.15; (b) 4 × 2c-2e N–N σ bonds, ON = 1.65|e|, iso-value = 0.2; (c) 2 × 2c-2e N–N π bonds, ON = 1.65|e|, iso-value = 0.1; (d) 1 × 4c-2e N–N large π bond, ON = 1.70|e|, iso-value = 0.03.
Fig. 7. Enthalpy of formation of P4/nmm-BeN4 relative to Be3N2 and N2.
Space group | Pressure (GPa) | Lattice parameter (Å°) | Atom | Wyckoff position | x | y | z |
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P4/nmm | 0 | a = 5.03 | α = 90.00 | Be | 4e | 0.500 | 0.500 | 0.500 | | | b = 5.03 | β = 90.00 | N | 16k | 0.000 | 0.692 | 0.327 | | | c = 4.21 | γ = 90.00 | | | | | |
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Table 1. Lattice parameters and atomic positions for P4/nmm-BeN4 at 0 GPa.
| | P4/nmm | Be3N2 |
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Elastic stiffness constants Cij | C11 | 224.82 | 517.77 | C22 | | | C33 | 20.82 | 479.98 | C44 | 111.15 | 190.16 | C55 | 2.29 | | C66 | 2.29 | 185.58 | C12 | 6.21 | 137.45 | C13 | 20.32 | 87.57 | B (GPa) | | 41.75 | 237.18 | G (GPa) | | 41.06 | 192.14 | E (GPa) | | 92.78 | 453.87 | v | | 0.13 | 0.18 | k | | 1.02 | |
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Table 2. Elastic constants of P4/nmm-BeN4 and Be3N2 at ambient pressure.
Compound | ρ (g/cm3) | Ed (kJ/g) | Vd (km/s) | Pd (kbar) |
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P4/nmm-BeN4 | 1.01 | 3.92 | 7.35 | 158.11 | TNT | 1.64a | 4.30b | 6.90c | 190.00a | HMX | 1.90a | 5.70b | 9.10c | 393.00a |
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Table 3. Detonation properties of P4/nmm-BeN4, TNT, and HMX.