压缩富氢化合物作为室温超导的潜在候选材料已受到广泛关注，然而，稳定这类材料所需的高压阻碍了其广泛的实际应用。为了寻找在低压下稳定的潜在超导氢化物，我们基于第一性原理计算研究了四元氢化物XM3Be4H32（X, M = Ca, Sr, Ba, Y, La, Ac, Th）的晶体结构和性质。我们在20 GPa的中压下确定了九个动力学稳定的化合物。引人注目的是，它们的超导转变温度远高于液氮温度，尤其是CaTh3Be4H32（在5 GPa下为124 K）、ThLa3Be4H32（在10 GPa下为134 K）、LaAc3Be4H32（在20 GPa下为135 K）和AcLa3Be4H32（在20 GPa下为153 K）在温和压力下表现出优异的超导电性。金属原子作为预压缩器向氢提供丰富的电子，削弱了H-H共价键，从而促进了氢亚晶格的金属化。同时，具有不同离子半径和电负性的金属元素的适当组合可以有效调节费米能级附近的电子结构并提高超导电性。这些发现充分揭示了四元氢化物在中压下承载高温超导性的巨大潜力，并将进一步促进相关探索。
英文摘要：
The compressed hydrogen-rich compounds have received extensive attention as promising candidates for room temperature superconductivity, however, the high pressure required to stabilize such materials hinders their wide practical application. In order to search for potential superconducting hydrides that are stable at low pressures, we have investigated the crystal structures and properties of quaternary hydrides, XM3Be4H32 (X, M = Ca, Sr, Ba, Y, La, Ac, Th) based on the first-principles calculations. We identified nine dynamically stable compounds at moderate pressure of 20 GPa. Strikingly, their superconducting transition temperatures are much higher than that of liquid nitrogen, especially CaTh3Be4H32 (124 K at 5 GPa), ThLa3Be4H32(134 K at 10 GPa), LaAc3Be4H32 (135 K at 20 GPa) and AcLa3Be4H32 (153 K at 20 GPa) exhibit outstanding superconductivity at mild pressures. Metal atoms acting as pre-compressors donate abundant electrons to hydrogen, weakening the H-H covalent bond and thus facilitating the metallization of the hydrogen sublattice. At the same time, the appropriate combination of metal elements with different ionic radius and electronegativity can effectively tune the electronic structure near the Fermi level and improve the superconductivity. These findings fully reveal the great promise of hosting high-temperature superconductivity of quaternary hydrides at moderate pressures and will further promote related exploration.
Ambient and Pressure Dependent Superconductivity with Hydrogen Storage Potential in Quaternary Hydride LiMgZr2H12: A Comprehensive First-principles Insights
Department of Physics, University of Rajshahi（拉杰沙希大学物理系）
Hydrides offer an opportunity to study high-temperature (Tc) superconductivity at experimentally achievable pressures. However, they remained extremely high. Using density functional theory calculations, herein we demonstrated that a newly rare earth hydride, namely bulk ErH2, could be superconducting with a Tc around 80 K at 14.5 GPa. To date, the drived pressure is the lowest reported value for compressed hydrides. Besides superconductivity, Fermi Surface nesting and Kondo effect were manifested at this pressure. Intriguingly, due to Kondo destruction, superconductivity was prone to exist at…
Hydrogen-based superconductors provide a route to the long-sought goal of room-temperature superconductivity, but the high pressures required to metallize these materials limit their immediate application. For example, carbonaceous sulfur hydride, the first room-temperature superconductor, can reach a critical temperature (Tc) of 288 K only at the extreme pressure of 267 GPa. The next recognized challenge is the realization of room-temperature superconductivity at significantly lower pressures. Here, we propose a strategy for the rational design of high-temperature superconductors at low press…
Inspired by the high critical temperature in yttrium superhydride and the low stabilized pressure in superconducting cerium superhydride, we carry out four independent runs to synthesize yttrium-cerium alloy hydrides. The phases examined by the Raman scattering and x-ray diffraction measurements. The superconductivity is detected with the zero-resistance state at the critical temperature in the range of 97-140 K at pressures ranging from 114 GPa to 120$\pm$4 GPa. The maximum critical temperature of the synthesized hydrides is larger than those reported for cerium hydrides, while the correspond…
Room temperature superconductivity is a dream that mankind has been chasing for a century. In recent years, the synthesis of H3S, LaH10 and C-S-H system has gradually made this dream a reality. But the extreme pressures required for the metallization of hydrogen-based superconductors limit their applications. In this work, we design a series of high temperature superconductors that can be stable at moderate pressures by incorporating heavy rare earth elements Yb/Lu into sodalite-like clathrate hydrides. In particular, the critical temperatures of Y3LuH24, YLuH12 and YLu3H24 are 283 K, 275 K an…
High-pressure structural searches of superhydrides CeBeH$_8$ and CeBH$_8$ were performed under ambient pressure up to 300 GPa. We identify $Fm\overline{3}m$-CeBeH$_8$ with a superconducting transition temperature $T_{c}$ of 56 K at 10 GPa. Two more phases with spacegroup $R\overline{3}m$ and $C2/m$, were investigated within the increasing pressures. CeBH$_8$ shows a similar phase transition process as CeBeH$_8$ but with higher transition pressures and higher $T_c$. $Fm\overline{3}m$-CeBH$_8$ is predicted to be superconducting above 120 GPa with a maximum $T_{c}$ of 118 K at 150 GPa. $R\overlin…
A-15 type superconducting hydride $La_4H_{23}$: Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity
The extreme pressures required to stabilize the recently discovered superhydrides represent a major obstacle to their practical application. In this paper, we propose a novel route to attain high-temperature superconductivity in hydrides at ambient pressure, by doping commercial metal borohydrides. Using first-principles calculations based on Density Functional Theory and Migdal-Eliashberg theory, we demonstrate that in Ca(BH$_4$)$_2$ a moderate hole doping of 0.03 holes per formula unit, obtained through a partial replacement of Ca with monovalent K, is sufficient to achieve $T_c$'s as high a…
Inorganic electrides are a new class of compounds catering to the interest of scientists due to the multiple usages exhibited by interstitial electrons in the lattice. However, the influence of the shape and distribution of interstitial electrons on physical properties and new forms of physical states are still unknown. In this work, crystal structure search algorithms are employed to explore the possibility of forming new electrides in the As-Li system, where interstitial electrons behave as 1D electron chains (1D electride) in Pmmm phase of AsLi$_7$ and transform into 0D electron clusters (0…
Discovery of high-temperature superconductivity in hydrogen-rich compounds has fuelled the enthusiasm for finding materials with more promising superconducting properties among hydrides. However, the ultrahigh pressure needed to synthesize and maintain high-temperature hydrogen-rich superconductors hinders the experimental investigation of these materials. For practical applications, it is also highly desired to find more hydrogen-rich materials that superconduct at high temperatures but under relatively lower pressures. Based on first-principles density functional theory, we calculate the ele…
Structural and Vibrational Properties of D$_3$Se from First Principles: Anharmonic Quantum and Isotope Effects
College of Science, Northeast Electric Power University（东北电力大学理学院）；Department of Applied Physics, School of Sciences, Xi’an University of Technology（西安理工大学理学院应用物理系）；Oden Institute for Computational Engineering and Sciences, University of Texas at Austin（德克萨斯大学奥斯汀分校奥登计算工程与科学研究所）
Intuitively, doping represents one of the most promising avenues for optimization of best prospect superconductors (SC) such as conventional high-pressure SCs with record critical temperatures. However, doping at high pressure (HP) is very challenging, and there is not a proved route to achieve it in a controlled fashion. Aided by computing simulations, we show that it may be plausible to start by alloying primary materials and subsequently incorporate high ratios of hydrogen at moderates pressures ($\approx$1.5 Mbar). Our theoretical results evidence the possibility to tune the electronic str…
