Phase Diagram and Superconductivity of Calcium Borohyrides at Extreme Pressures

Abstract

Motivated by the recent discovery of near-room temperature superconductivity in high-pressure superhydrides, we investigate from first-principles the high-pressure superconducting phase diagram of the ternary Ca-B-H system, using ab-initio evolutionary crystal structure prediction, and Density Functional Perturbation Theory. We find that below 100 GPa all stable and weakly metastable phases are insulating. This pressure marks the appearance of several new chemically-forbidden phases on the hull of stability, and the first onset of metalization in CaBH${}_5$. Metallization is then gradually achieved at higher pressure at different compositions. Among the metallic phases stable in the Megabar regime, we predict two high-$T_c$ superconducting phases with CaBH${}_6$ and Ca${}_2$B${}_2$H${}_{13}$ compositions, with critical temperatures of 119 and 89 K at 300 GPa, respectively, surviving to lower pressures. Ternary hydrides will most likely play a major role in superconductivity research in the coming years; our study suggests that, in order to reduce the pressure for the onset of metallicity and superconductivity, further explorations of ternary hydrides should focus on elements less electronegative than boron.

References in corpus (31)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Phonons and related properties of extended systems from density-functional perturbation theory
• Conventional superconductivity at 203 K at high pressures
• Superconductivity at 250 K in lanthanum hydride under high pressures
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• Superconductive "sodalite"-like clathrate calcium hydride at high pressures
• Superconductivity of MgB2: Covalent Bonds Driven Metallic
• The metallization and superconductivity of dense hydrogen sulfide
• High-pressure phases of silane
• Electron-phonon interactions and related physical properties of metals from linear-response theory
• A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride
• Superconductivity at 161 K in Thorium Hydride $Th{H}_{10}$: Synthesis and Properties
• Superconducting hydrides under pressure
• Three-dimensional MgB${}_2$-type superconductivity in hole-doped diamond
• High temperature superconductivity in sulfur and selenium hydrides at high pressure
• On Distribution of Superconductivity in Metal Hydrides
• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Superconductivity in sodalite-like yttrium hydride clathrates
• Superconductivity in metastable phases of phosphorus-hydride compounds under high pressure
• Influence of bonding on superconductivity in high-pressure hydrides
• Possible Superconductivity Approaching Ice Point
• Superconductivity up to 243 K in yttrium hydrides under high pressure
• Possible "Magnéli" phases and self-alloying in the superconducting sulfur hydride
• Superconductivity above 100 K in PH3 at high pressures
• Prediction of High-Tc conventional Superconductivity in the Ternary Lithium Borohydride System
• Thermodynamics and superconductivity of S${}_x$Se${}_{1-x}$H${}_3$
• Stability and superconductivity of Ca-B phases at ambient and high pressure
• Absence of superconductivity in iron polyhydrides at high pressures
• Superconductivity and unexpected chemistry of germanium hydrides under pressure

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