Nitrogen-hydrogen-oxygen ternary phase diagram: New phases at high pressure from structural prediction
Nitrogen-hydrogen-oxygen ternary phase diagram: New phases at high pressure from structural prediction
复制标题
DOI：
10.1103/physrevmaterials.2.023604
复制
发表时间：
2018-02-21
影响因子：
3.4
通讯作者：
Marques, Miguel A. L.
中科院分区：
文献类型：
--
作者：
Shi, Jingming;Cui, Wenwen;Marques, Miguel A. L.
利用从头算进化结构搜索，我们预测了两个新的晶相在H-N-O三元相图在高压下，即NOH 4和HNO 3（硝酸）。计算结果表明，NOH 4的C2/m相在71 GPa时稳定，HNO 3的P2（1）/m相在39 GPa时稳定.这两个阶段保持稳定，至少高达150 GPa，我们考虑的最大压力。NOH_4的C_2/m相由两个NH_3分子通过N-N共价键连接而成，含有两个O-H层和一个哑铃团簇层。HNO 3的P2（1）/m相含有由H-N-O共价键形成的令人惊讶的准情人层。进一步的计算表明，这两个阶段是半导体，与带隙为6.0和2.6 eV的NOH 4和NHO 3，分别。我们的计算还证实，化合物NOH 5（NH3 H2O）在122 GPa以上的压力变得不稳定，分解成NH3和H2O。
Using an ab initio evolutionary structural search, we predict two novel crystalline phases in the H-N-O ternary phase diagram at high pressure, namely, NOH4 and HNO3 (nitric acid). Our calculations show that the C2/m phase of NOH4 becomes stable at 71 GPa, while the P2(1)/m phase of HNO3 stabilizes at 39 GPa. Both phases remain thermodynamically stable at least up to 150 GPa, the maximum pressure we considered. The C2/m phase of NOH4 contains two O-H layers and one dumbbell cluster layer, formed by two NH3 molecules linked by a N-N covalent bond. The P2(1)/m phase of HNO3 contains a surprising quasiclover layer formed of H-N-O covalent bonds. Further calculations showthat both phases are semiconducting, with band gaps of 6.0 and 2.6 eV for NOH4 and NHO3, respectively. Our calculations also confirm that the compound NOH5 (NH3H2O) becomes unstable at pressures above 122 GPa, decomposing into NH3 and H2O.