论文标题
在压力下
Potential high-$T_{c}$ superconductivity in YCeH$_{x}$ and LaCeH$_{x}$ under pressure
论文作者
论文摘要
灯笼，Yttrium和hydride是三个最著名的超导二元氢化物（La-H，Y-H和CE-H系统），在理论和实验研究中都引起了人们的关注。最近的研究表明，由灯笼和Yttrium组成的三元氢化物可以在253 K左右实现高超导性。在这项研究中，我们采用了基于进化的基于进化的晶体结构预测（CSP）方法和第一原则计算，以研究组成（Y，CE）和高压的三分光液压的稳定性和超导性。我们的计算表明，Y-CE-H和LA-CE-H系统中存在多个稳定阶段，其中$ p4/mmm $ -yceh $ _ {8} $，$ p \ bar {6} m2 $ -yceh $ _ {18} $ $P4/mmm$-LaCeH$_{8}$, and $R\bar{3}m$-LaCeH$_{20}$ possessing H$_{18}$, H$_{29}$ and H$_{32}$ clathrate structures can maintain both the thermodynamic and lattice-dynamic stabilities.此外，我们还发现这些阶段在高温下还保持着对分解的强烈抗性。电子 - 光子耦合计算表明，这五个阶段中只有三个可以表现出高温超导性。 $ r \ bar {3} m $ -yceh $ _ {20} $，$ r \ bar {3} m $ -laceh $ _-laceh $ _ {20} $ {20} $ {20} $ {6} $ p \ bar {6} m2 $ - Allen-Dynes修饰的McMillan公式分别为300 GPA，250 GPA的116 K和150 GPA的173 K为122 K。此外，稳定$ p \ bar {6} m2 $ -yceh $ _ {18} $的压力可以降低至150 GPA，这表明其高压合成的条件可访问。
Lanthanum, yttrium, and cerium hydrides are the three most well-known superconducting binary hydrides (La-H, Y-H, and Ce-H systems), which have gained great attention in both theoretical and experimental studies. Recent studies have shown that ternary hydrides composed of lanthanum and yttrium can achieve high superconductivity around 253 K. In this study we employ the evolutionary-algorithm-based crystal structure prediction (CSP) method and first-principles calculations to investigate the stability and superconductivity of ternary hydrides composed of (Y, Ce) and (La, Ce) under high pressure. Our calculations show that there are multiple stable phases in Y-Ce-H and La-Ce-H systems, among which $P4/mmm$-YCeH$_{8}$, $P\bar{6}m2$-YCeH$_{18}$, $R\bar{3}m$-YCeH$_{20}$, $P4/mmm$-LaCeH$_{8}$, and $R\bar{3}m$-LaCeH$_{20}$ possessing H$_{18}$, H$_{29}$ and H$_{32}$ clathrate structures can maintain both the thermodynamic and lattice-dynamic stabilities. In addition, we also find that these phases also maintain a strong resistance to decomposition at high temperature. Electron-phonon coupling calculations show that only three of these five phases can exhibit high-temperature superconductivity. The superconducting transition temperatures ($T_\mathrm{c}$) of $R\bar{3}m$-YCeH$_{20}$, $R\bar{3}m$-LaCeH$_{20}$, and $P\bar{6}m2$-YCeH$_{18}$ are predicted using the Allen-Dynes-modified McMillan formula to be 122 K at 300 GPa, 116 K at 250 GPa, and 173 K at 150 GPa, respectively. Moreover, the pressure to stabilize $P\bar{6}m2$-YCeH$_{18}$ can be lowered to 150 GPa, suggesting an accessible condition for its high-pressure synthesis.
