$\mathcal{P}^2$：结合压力和电化学合成超导体
$\mathcal{P}^2$: Combining pressure and electrochemistry to synthesize superhydrides
摘要：
最近，超导体已经被计算确定，并随后在非常高的压力下与各种金属合成。在这项工作中，我们评估的可能性，合成超导独特的结合电化学和施加压力。我们使用密度泛函理论和粒子群优化计算在很宽的压力和电极电位范围内进行钯超导体的计算搜索。我们将交换相关功能的不确定性，使用贝叶斯误差估计形式主义量化的不确定性与确定的稳定阶段。基于热力学分析，我们构建了压力-势相图，并提供了一个替代的合成概念，$\mathcal{P}^2$（压力-势），访问新的阶段具有高的氢含量。钯-氢是一种被广泛研究的材料体系，其中最高的氢化物相为Pd $_3$ H $_4$。对于该系统最引人注目的是，在高于析氢的电势和$\sim$ 300 MPa的压力下，我们发现了制备钯超氧化物的可能性（例如，PdH $_{10}$）。我们证明了这种方法对于La-H，Y-H和Mg-H的普遍性，稳定相所需的压力降低了10-100倍。此外，$\mathcal{P}^2$策略允许稳定新相，这些新相不能纯粹通过压力或势来完成，并且是可能在适度压力下用于合成其他超临界流体的一般方法。
英文摘要：
Recently, superhydrides have been computationally identified and subsequently synthesized with a variety of metals at very high pressures. In this work, we evaluate the possibility of synthesizing superhydrides by uniquely combining electrochemistry and applied pressure. We perform computational searches for palladium superhydrides using density functional theory and particle swarm optimization calculations over a broad range of pressures and electrode potentials. We incorporate exchange-correlation functional uncertainty using the Bayesian error estimation formalism to quantify the uncertainty associated with the identified stable phases. Based on a thermodynamic analysis, we construct pressure-potential phase diagrams and provide an alternate synthesis concept, $\mathcal{P}^2$ (pressure-potential), to accessing novel phases having high hydrogen content. Palladium-hydrogen is a widely-studied material system with the highest hydride phase being Pd$_3$H$_4$. Most strikingly for this system, at potentials above hydrogen evolution and $\sim$300 MPa pressure, we find the possibility to make palladium superhydrides (e.g., PdH$_{10}$). We demonstrate the generalizability of this approach for La-H, Y-H and Mg-H with 10-100 fold reduction in required pressure for stabilizing phases. In addition, the $\mathcal{P}^2$ strategy allows stabilizing new phases that cannot be done purely by either pressure or potential and is a general approach that is likely to work for synthesizing other superhydrides at modest pressures.
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