Superconductivity and unexpected chemistry of germanium hydrides under pressure
Superconductivity and unexpected chemistry of germanium hydrides under pressure
复制标题
DOI：
10.1103/physrevb.95.134506
复制
发表时间：
2017-04-10
影响因子：
3.7
通讯作者：
Zhang, Jin
中科院分区：
文献类型：
--
作者：
Esfahani, M. Mahdi Davari;Oganov, Artem R.;Zhang, Jin
基于富氢化合物在高压下可能是高温超导体的想法，以及最近在预测和合成具有历史最高T-c = 203 K的硫化氢方面的突破，采用从头算进化算法预测晶体结构以找到稳定的锗超导体。除了早期的结构锗烷与空间群Ama 2，我们提出了一个C2/m结构，这是积极的更有利的压力高于278 GPa（包括零点能）。计算结果表明，锗烷的C_2/m相是一种超导体，在280 GPa下，T_c = 67 K。发现锗烷在高于300 GPa的压力下变得对分解成氢和化合物Ge 3 H 11具有化学不稳定性。Ge_3 H_（11）空间群为I_4m_2，在285 GPa以上温度下稳定，Tc = 43 K。我们发现，压力诱导的锗晶体的相稳定性不同于类似的等电子系统，例如，Si和Sn。超导性源于与主要来自氢的摇摆、弯曲和拉伸中频模式相关的大的电子-声子耦合。
Following the idea that hydrogen-rich compounds might be high-T-c superconductors at high pressures, and the very recent breakthrough in predicting and synthesizing hydrogen sulfide with record-high T-c = 203 K, an ab initio evolutionary algorithm for crystal structure prediction was employed to find stable germanium hydrides. In addition to the earlier structure of germane with space group Ama2, we propose a C2/m structure, which is energetically more favorable at pressures above 278 GPa (with inclusion of zero-point energy). Our calculations indicate that the C2/m phase of germane is a superconductor with T-c = 67K at 280 GPa. Germane is found to become thermodynamically unstable to decomposition to hydrogen and the compound Ge3H11 at pressures above 300 GPa. Ge3H11 with space group I4m2 is found to become stable at above 285 GPa with T-c = 43 K. We find that the pressure-induced phase stability of germanium hydrides is distinct from analogous isoelectronic systems, e.g., Si hydrides and Sn hydrides. Superconductivity stems from large electron-phonon coupling associated with the wagging, bending, and stretching intermediate-frequency modes derived mainly from hydrogen.