Two-step synthesize superconducting hydride at lower pressures
Polyhydride superconductor was successfully synthesized at pressures much lower than what previously needed.
image: (a) Crystal structure sketches and coordination environment of Rh in Mg2RhH5 (P4/nmm) wherein the Rh ions are in a square pyramidal configuration with four H1 atoms in the basal plane and one H2 atom at the apex; (b) Crystal structure sketches and coordination environment of Rh for Mg2RhH6 (Fm3m) wherein Rh ions are coordinated by six H atoms forming an ideal octahedral configuration.
Credit: IOPCAS
The study is led by Prof. Changqing Jin form Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences.
The researchers synthesized Mg2RhH6 via a two-step process: first, preparing theMg2RhH5 precursor, in which hydrogen atoms are stabilized by covalent bonding; then, introducing additional hydrogen, which introduces electrons into antibonding orbitals above 30 GPa and simultaneously triggers a structural transition from RhH5 square pyramids to RhH6 octahedra. Experiments showed that Mg2RhH6 becomes superconducting at around 30 GPa. The sharp drop in resistivity to zero and the characteristic suppression of Tc at applied magnetic fields both confirm its superconductivity. The study also confirms that Mg2RhH6 is thermodynamically stable above 30 GPa, making it the first superconductor with a Tc of approximately 30 K at a readily accessible pressure for industrial pressure facilities. The findings open a highly promising pathway for the rational design and discovery of high temperature superconductors near accessible pressures within the phonon mediated BCS framework.
See the article:
“Superconducting Hydride Mg2RhH6 Experimentally Achieved at Lower Pressure”, Journal of the American Chemical Society 148, 36854~36862(2026).