Unconventional Stoichiometries of Na-O Compounds at High Pressures.
Unconventional Stoichiometries of Na-O Compounds at High Pressures.
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高压下 Na-O 化合物的非常规化学计量
DOI：
10.3390/ma14247650
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发表时间：
2021-12-12
期刊：
影响因子：
--
通讯作者：
Yang J
中科院分区：
文献类型：
--
作者：
Yang L;Zhang Y;Chen Y;Zhong X;Wang D;Lang J;Qu X;Yang J
人们已经认识到，化合物的化学计量在高压下可能会发生变化，这对于发现新材料至关重要。本工作采用系统的结构探索和第一性原理计算，考虑不同化学计量的Na-O化合物的稳定性相对于压力，从而构建了高压稳定性场和凸船体图。四个以前未知的化学计量（NaO 5，NaO 4，Na 4 O，和Na 3 O）被预测为化学稳定的。还发现了四种已知化学计量比的新相（P2/m和Cmc_（21）NaO_2和Imm和C2/mNaO_3），富氧化学计量比显示出所有氧原子都以准分子O_2单元存在的显著特征，并且是金属性的。通过对O-O键长和Bader电荷的计算，探讨了富氧化合物的电子性质和化学键。在极压（P > 200 GPa）下稳定的富钠化合物是具有强间隙电子局域化的化合物。发现Na_3O的C_2/c相是一个具有绝缘性质的零维晶体。Na_4 O的Cmca相是一维的金属氧化物。这些具有不寻常化学性质的新化合物的发现可能会刺激未来的实验和理论研究。
It has been realized that the stoichiometries of compounds may change under high pressure, which is crucial in the discovery of novel materials. This work uses systematic structure exploration and first-principles calculations to consider the stability of different stoichiometries of Na–O compounds with respect to pressure and, thus, construct a high-pressure stability field and convex hull diagram. Four previously unknown stoichiometries (NaO5, NaO4, Na4O, and Na3O) are predicted to be thermodynamically stable. Four new phases (P2/m and Cmc21 NaO2 and Immm and C2/m NaO3) of known stoichiometries are also found. The O-rich stoichiometries show the remarkable features of all the O atoms existing as quasimolecular O2 units and being metallic. Calculations of the O–O bond lengths and Bader charges are used to explore the electronic properties and chemical bonding of the O-rich compounds. The Na-rich compounds stabilized at extreme pressures (P > 200 GPa) are electrides with strong interstitial electron localization. The C2/c phase of Na3O is found to be a zero-dimensional electride with an insulating character. The Cmca phase of Na4O is a one-dimensional metallic electride. These findings of new compounds with unusual chemistry might stimulate future experimental and theoretical investigations.
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影响因子：
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