A novel superhard BN allotrope under cold compression of h-BN
A novel superhard BN allotrope under cold compression of h-BN
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DOI：
10.1088/0953-8984/25/12/122204
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
Xue Jiang;Jijun Zhao;R. Ahuja
中科院分区：
文献类型：
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作者：
Xue Jiang;Jijun Zhao;R. Ahuja
利用第一性原理计算，我们发现了一种新的斜方氮化硼（BN）相（即P-BN;空间群：Pmn 21），它具有与Bct-BN和Z-BN相似的拓扑结构，但没有六元环。这种P-BN同素异形体在能量上比先前报道的Pnma-BN、Bct-BN和Z-BN相更有利。在环境压力下，它的稳定性仅比h-BN低0.06 eV/原子，可以在4 GPa的低压下冷压缩下由h-BN形成。P-BN晶体的理论硬度和体积模量分别为403 GPa和60.5 GPa，与c-BN的理论硬度和体积模量相当。此外，P-BN相沿着Bct-BN和Z-BN可能是h-BN和w-BN之间的中间相，这可以用Ostwald和Ostwald-Volmer的两个经验规则定性地解释。
Using first-principles calculations, we identify a new orthorhombic boron nitride (BN) phase (namely, P-BN; space group: Pmn21), which has similar topological structure to Bct-BN and Z-BN, but without the six-membered ring. This P-BN allotrope is energetically more favorable than previously reported Pnma-BN, Bct-BN and Z-BN phases. With only 0.06 eV/atom less stable than h-BN at ambient pressure, it can be formed from h-BN under cold compression at a low pressure of 4 GPa. The theoretical hardness and bulk modulus of the P-BN crystal are 403 GPa and 60.5 GPa, respectively, comparable to those of c-BN. Moreover, the P-BN phase along with Bct-BN and Z-BN are suggested as possible intermediate phases between h-BN and w-BN, which can be qualitatively explained by two empirical rules of Ostwald and Ostwald–Volmer.