Metallization and Superconductivity in the Hydrogen-Rich Ionic Salt BaReH₉

Abstract

BaReH 9 is an exceedingly high hydrogen content metal hydride that is predicted to exhibit interesting behavior under pressure. The high-pressure electronic properties of this material were investigated using diamond-anvil cell electrical conductivity techniques to megabar (100 GPa) pressures. The measurements show that BeReH 9 transforms to a metal and then superconductor above 100 GPa with a maximum T c near 7 K. The occurrence of superconductivity is confirmed by the suppression of the resistance drop on application of magnetic fields. The transition to the metallic phase is sluggish, but is accelerated by laser irradiation. Raman scattering and x-ray diffraction measurements, used to supplement the electrical measurements, indicate that the Ba-Re sublattice is largely preserved on compression at the conditions explored, but there is a possibility that hydrogen atoms are gradually disordered under pressure. This is suggested from sharpening of peaks of Raman spectroscopy and x-ray diffraction by heat treatment as well as temperature dependence of resistance under pressure. The data suggest that the transition to the superconducting state is first order. The possibility that the transition is associated with the breakdown of BeReH 9 is discussed.

Ternary superconducting cophosphorus hydrides stabilized via lithium

“…High-pressure experiments found that the ternary hydride BaReH 9 is a superconductor with T c about 7 K at 100 GPa. 24 Also in theoretical work, the T c of Fe 2 SH 3 , 25 YS 4 H 4 , 26 and YSH 5 27 at 173, 200, and 300 GPa is about 0.3, 20, and 0.7 K, respectively. Earlier, through theoretical calculations, our group found that after the introduction of Mg in the insulating CH 4 system, the T c of MgCH 4 can reach 120 K at 121 GPa.…”

First-principles study of crystal structures and superconductivity of ternary YSH6 and LaSH6 at high pressures

“…Such achievements enhanced the interest in further searching possible room-temperature superconducting hydrides, and ternary hydrogen-rich compounds are interesting candidates. BaReH 9 was reported experimentally to be a superconductor under pressure, with a T c of about 7 K above 100 GPa [22]. Ba(AuH 2 ) 2 and Sr(AuH 2 ) 2 were predicted to be superconductors below 30 and 10 K at 1 atm, respectively [23].…”

Route to a Superconducting Phase above Room Temperature in Electron-Doped Hydride Compounds under High Pressure

“…There have been few studies on the superconductivity of compressed ternary hydrides [27][28][29][30][31][32][33][34][35][36][37][38][39][40]. Experimental examples include BeReH 9 [27] and Li 5 MoH 11 [28] synthesized under high-pressure conditions and showing unexpectedly low T c < 10 K. Crystal structure prediction simulations for ternary systems are computationally demanding.…”