First-Principles Investigations on Structural Transformation and Electronic Properties of BeP2N4 under High Pressure
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摘要: 基于密度泛函理论的第一性原理方法,计算了硅铍石型和尖晶石型结构BeP2N4的总能量随体积的变化关系。利用Brich-Murnaghan状态方程,通过能量和体积拟合,得到了2种结构的体变模量及其对压强的一阶导数。在压力作用下,BeP2N4的相变是从硅铍石型结构(空间群R-3,No.148)转变到尖晶石型结构(空间群Fd-3m,No.227),计算出的相变点与其它理论值符合得非常好。同时计算了BeP2N4的相对晶格常数a/a0和相对体积V/V0的压缩率,在低压下发现,尖晶石结构BeP2N4的压缩率接近金刚石,进一步计算了不同压力下的体弹模量BH、剪切模量GH、BH/GH和杨氏模量E。此外,对两种结构的BeP2N4的电子态密度和带隙随压强的变化关系进行了计算和分析。结果表明:在压力作用下,上价带顶向费米能级移动,并有一定的展宽。BeN、PN键缩短,电子转移增加,导致电荷发生重新分布。Abstract: Total energy of BeP2N4 as a function of unit cell volume was calculated for phenakite and spinel-type structures using the density function theory (DFT). According to the Brich-Murnaghan's equation of state, the bulk modulus B0 and B0=dB/dp for these two structures were obtained. The calculated results are all in good agreement with other theoretical data available in the literature, which indicate that BeP2N4 will transform from phenakite to spinel-type with increasing pressure. The results are in good agreement with experimental and other theoretical results. The energy gap slightly increases with pressure in the phenakite and spinel-type phases. The compression ratio of a/a0 and V/V0 were calculated. We find the the compression ratio of a/a0 and V/V0 of spinel structure BeP2N4 is the same that of diamond at lower 5 GPa. The BH, GH, BH/GH and E were also calculated at high pressure. By analyzing the changes of the total electronic density of states (TDOS) and the band gap under pressure, it is found that the energy band width and charge transfer for the two structures increase with increasing pressure. Moreover, the BeN, PN bond length is shortened and the electric charges are redistributed.
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Zerr A, Miehe G, Serghiou G, et al. Synthesis of cubic silicon nitride [J]. Nature(London), 1999, 400: 340-342. Jiang J Z, Kragh F, Frost D J, et al. Hardness and thermal stability of cubic silicon nitride [J]. J Phys: Condens Mater, 2001, 13: L515- L520. Leinenweber K, O'Keeffe M, Somayazulu M, et al. Synthesis and structure refinement of the spinel-Ge3N4 [J]. Chem Eur J, 1999, 5: 3076-3078. Serghiou G, Miehe G, Tschauner O, et al. Synthesis of a cubic Ge3N4 phase at high pressures and temperatures [J]. J Chem Phys, 1999, 111(10): 4659-4662. Scotti N, Kockelmann W, Senker J, et al. Sn3N4, a tin (Ⅳ) nitride-Syntheses and the first crystal structure determination of a binary tin-nitrogen compound [J]. Z Anorg Allg Chem, 1999, 625: 1435-1439. Shemkunas M P, Wolf G H, Leinenweber K, et al. Rapid synthesis of crystalline spinel tin nitride by a solid-state metathesis reaction [J]. J Am Ceram Soc, 2002, 85: 101-104. Zerr A, Miehe G, Riedel R. Synthesis of cubic zirconium and hafnium nitride having Th3P4 structure [ J]. Nature Matter, 2003, 2: 185-189. Gregoryanz E, Sanloup C, Somayazulu M, et al. Synthesis and char acterization of a binar y noble metal nitride [ J]. Nature Mater, 2004, 3: 294-297. Corwhurst J C, Goncharov A F, Sadigh B, et al. Synthesis and characterization of the nitrides of platinum and iridium [J]. Science, 2006, 311: 1275-1278. Karau F W, Seyfarth L, Oeckler O. The stuffed framework structure of SrP2N4: Challenges to synthesis and crystal structure determination [J]. Chem Eur J, 2007, 13: 6841-6852. Karau F, Schnick W. Hochdrucksynthese von BaSr2P6N12 und BaCa2P6N12 und strukturvergleich der reihe BaP2N4, BaCa2P6N12 und BaSr2P6N12 [J]. Z Anorg Allg Chem, 2006, 632: 231-237. Pucher F J, Rmer S R, Karau F W, et al. Phenakite-type BeP2N4-A possible precursor for a new hard spinel-type material [J]. Chem Eur J, 2010, 16(24): 7208-7214. Perdew J P, Burke K, Ernzerhof M. Generalized gradient approximation made simple [J]. Phys Rev Lett, 1996, 77: 3865-3868. Brich F. Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300 K [J]. J Geophys Res, 1978, 83: 1257-1268. Xiao B, Xing J D, Feng J, et al. Theoretical study on the stability and mechanical property of Cr7C3 [J]. Phys B, 2008, 403: 2273-2281. Feng J, Chen J C, Xiao B, et al. Stability, thermodynamic and mechanical properties of the compounds in the Ag-Sn-O system [J]. Phys B, 2009, 404: 2461-2467. Jaffe J E, Hess A C. Hartree-fock study of phase changes in ZnO at high pressure [J]. Phys Rev B, 1993, 48: 7903-7909. Kalpana G, Palanivel B, Rajagopalan M. Electronic structure and structura l phase stability in BaS, BaSe and BaTe [J]. Phys Rev B, 1994, 50: 12318-12325. Ding Y C, Xiao B. Theoretical study on electronic structure, elastic properties and intrinsic hardness of a new superhard material BeP2N4 [J]. Acta Phys-Chim Sin, 2011, 27(7): 1621-1632. (in Chinese) 丁迎春, 肖冰. 一种超硬新材料BeP2N4的电子结构和力学性质及本征硬度 [J]. 物理化学学报, 2011, 27(7): 1621-1632. Gao F M. Theoretical model of intrinsic hardness [J]. Phys Rev B, 2006, 73: 132104-132107. Li Y F, Gao Y M, Xiao B, et al. The electronic, mechanical properties and theoretical hardness of chromium carbides by first-principles calculations [J]. J Alloys Compd, 2011, 509: 5242-5249.
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