Novel magnesium borides and their superconductivity
Novel magnesium borides and their superconductivity
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DOI：
10.1039/c7cp00840f
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发表时间：
2017-06-14
影响因子：
3.3
通讯作者：
Zhou, Xiang-Feng
中科院分区：
文献类型：
--
作者：
Esfahani, M. Mahdi Davari;Zhu, Qiang;Zhou, Xiang-Feng
为了在Mg-B体系中寻找新的超导体，我们在0-200 GPa压力范围内对该二元体系中所有稳定的化合物进行了从头算进化搜索。我们发现了以前未知的，但结晶稳定的组合物MgB 3和Mg3 B10。实验上已知的MgB 2在0-200 GPa的整个压力范围内是稳定的，而MgB 7和MgB 12分别在低于90 GPa和35 GPa的压力下是稳定的。我们预测的重入行为的MgB 4，它变得不稳定，对分解成MgB 2和MgB 7在4 GPa，然后变得稳定以上61 GPa。我们发现无处不在的阶段与硼三明治结构类似的AlB 2型结构。然而，除了MgB 2之外，所有其他硼化镁都具有0.32-0.39的低电子-声子耦合常数λ，并且预测具有低于3 K的T-c。
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 MgB3 and Mg3B10. Experimentally known MgB2 is stable in the entire pressure range 0-200 GPa, while MgB7 and MgB12 are stable at pressures below 90 GPa and 35 GPa, respectively. We predict a reentrant behavior for MgB4, which becomes unstable against decomposition into MgB2 and MgB7 at 4 GPa and then becomes stable above 61 GPa. We find ubiquity of phases with boron sandwich structures analogous to the AlB2-type structure. However, with the exception of MgB2, all other magnesium borides have low electron-phonon coupling constants lambda of 0.32-0.39 and are predicted to have T-c below 3 K.