High-temperature superconductivity in M2BH6 hydrides under near ambient pressure

Weiguo Sun; Simin Li; Xiaofeng Li; Feifei Qiu; Bole Chen; Cheng Lu; Andreas Hermann; Feng Peng

doi:10.1103/xw5d-vsyg

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High-temperature superconductivity in M2BH6 hydrides under near ambient pressure

Weiguo Sun, Simin Li, Xiaofeng Li, Feifei Qiu, Bole Chen, Cheng Lu, Andreas Hermann, Feng Peng

DOI 10.1103/xw5d-vsyg · Physical Review B

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Abstract

Hydrogen-rich compounds that exhibit high-temperature superconductivity typically require extreme pressures, which severely limits their practical applicability. Recent theoretical predictions of the complex hydride Mg2IrH6 have introduced a new family of M2XH6-type hydrides, highlighting the potential for high-temperature superconductivity at near-ambient pressure. Motivated by this, we have performed high-throughput first-principles investigations of the M2XH6 family (M = IA, IIA, IIIA, IIB metals; X = B, C, N) to identify dynamically stable hydrides and explore their superconducting properties. Eleven boron-based hydrides, M2BH6 (M = Li, Na, K, Rb, Cs, Ca, Sr, Ba, Sc, Y, La), featuring BH6 octahedral units have been identified. Notably, Li2BH6 is dynamically stable down to 16 GPa and exhibits a superconducting critical temperature of 121.25 K. Electronic structure and phonon analyses indicate that high-frequency hydrogen vibrations from strong B–H covalent bonding, reinforced by light Li atoms, dominate the electron–phonon coupling. In contrast, noble-metal-based Li2XH6 compounds (X = Cu, Ag, Au) exhibit distinct superconducting mechanisms, driven by d electrons at the Fermi level and low-frequency metal vibrations. These findings expand the compositional space of the M2XH6 family and highlight Li2BH6 as a promising candidate for near-ambient-pressure high-Tc superconductivity.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Li2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	121.25	16 GPa	unknown
Li2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	121.66	25 GPa	unknown
Li2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	121.52	50 GPa	unknown
Li2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	98	100 GPa	unknown
Li2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	81	200 GPa	unknown
Li2CuH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	99.65	Pressure unresolved	unknown
Li2AgH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	67.95	5 GPa	unknown
Li2AgH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	87.78	10 GPa	unknown
Li2AuH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	80.48	Pressure unresolved	unknown
Na2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	35.38	5 GPa	unknown
Na2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	38.66	10 GPa	unknown
Na2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	46.32	50 GPa	unknown
K2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	12.43	Pressure unresolved	unknown
Rb2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.85	Pressure unresolved	unknown
Cs2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8.15	Pressure unresolved	unknown
Ca2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22.22	10 GPa	unknown
Sr2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30.33	1 GPa	unknown
Sr2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	45.27	5 GPa	unknown
Ba2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.35	Pressure unresolved	unknown
Sc2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	23.4	12 GPa	unknown
Sc2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10.67	15 GPa	unknown
Y2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	18.8	5 GPa	unknown
La2BH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.1	Pressure unresolved	unknown