Phase diagrams and superconductivity of ternary Na-Al-H compounds at high pressure

Hao Song; Zihan Zhang; Mingyang Du; Qiwen Jiang; Defang Duan; Tian Cui

doi:10.1103/PhysRevB.104.104509

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Phase diagrams and superconductivity of ternary Na-Al-H compounds at high pressure

Hao Song, Zihan Zhang, Mingyang Du, Qiwen Jiang, Defang Duan, Tian Cui

DOI 10.1103/PhysRevB.104.104509 · Physical Review B

T1

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Abstract

Invigorated by the high-temperature superconductivity in ternary hydrogen-dominated compounds under high pressures, we systematically explored high-pressure phase diagrams, electronic properties, lattice dynamics, and superconductivity of ternary Na-Al-H systems using ab initio methods. We found three stable compounds of NaAlH4, NaAlH6, and NaAlH8, as well as a metastable compound of NaAlH7 under high pressures. Except for NaAlH4, they all containing H− and H2 units. Electronic structure calculations reveal that NaAlH7 and NaAlH8 are metallic, while NaAlH4 and NaAlH6 are semiconductors. In addition, NaAlH8 exhibits a phonon anomaly (dip) in multiple phonon branches along the A-M direction. The phonon anomaly induced by Fermi-surface nesting boosts the electron-phonon coupling strength, and as a result, a superconducting transition temperature Tc of 55 K was produced at 300 GPa.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NaAlH8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	55	300 GPa	unknown
SiH3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	139	275 GPa	unknown
CaH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	235	150 GPa	unknown
YH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	264	120 GPa	unknown
HfH10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	234	250 GPa	unknown
TeH4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	104	170 GPa	unknown
H3S Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	203	Pressure not reported	unknown
LaH10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	250	Pressure not reported	unknown
MgSiH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	unknown
MgGeH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	unknown
LiPH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	150	200 GPa	unknown
Li2MgH16 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	473	250 GPa	unknown
BaReH9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	7	100 GPa	unknown