Davari Esfahani M Mahdi, Zhu Qiang, Dong Huafeng, Oganov Artem R, Wang Shengnan, Rakitin Maksim S, Zhou Xiang-Feng
Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794-2100, USA.
Phys Chem Chem Phys. 2017 Jun 7;19(22):14486-14494. doi: 10.1039/c7cp00840f.
With the motivation of searching for new superconductors in the Mg-B system, we performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0-200 GPa. We found previously unknown, yet thermodynamically stable, compositions MgB and MgB. Experimentally known MgB is stable in the entire pressure range 0-200 GPa, while MgB and MgB are stable at pressures below 90 GPa and 35 GPa, respectively. We predict a reentrant behavior for MgB, which becomes unstable against decomposition into MgB and MgB at 4 GPa and then becomes stable above 61 GPa. We find ubiquity of phases with boron sandwich structures analogous to the AlB-type structure. However, with the exception of MgB, all other magnesium borides have low electron-phonon coupling constants λ of 0.32-0.39 and are predicted to have T below 3 K.
出于在Mg-B体系中寻找新型超导体的动机，我们对该二元体系在0至200吉帕压力范围内的所有稳定化合物进行了从头算进化搜索。我们发现了先前未知但热力学稳定的成分MgB和MgB。实验已知的MgB在0至200吉帕的整个压力范围内都是稳定的，而MgB和MgB分别在90吉帕和35吉帕以下的压力下是稳定的。我们预测MgB会出现再入行为，它在4吉帕时会分解成MgB和MgB而变得不稳定，然后在61吉帕以上变得稳定。我们发现具有类似于AlB型结构的硼夹心结构的相普遍存在。然而，除了MgB之外，所有其他硼化镁的电子-声子耦合常数λ都很低，为0.32至0.39，预计其超导转变温度T低于3K。
