Hot Hydride Superconductivity above 550 K

Abstract

The search for room temperature superconductivity has accelerated dramatically in the last few years driven largely by theoretical predictions that first indicated alloying dense hydrogen with other elements could produce conventional phonon-mediated superconductivity at very high temperatures and at accessible pressures, and more recently, with the success of structure search methods that have identified specific candidates and pressure-temperature (P-T) conditions for synthesis. These theoretical advances have prompted improvements in experimental techniques to test these predictions. As a result, experimental studies of simple binary hydrides under pressure have yielded high critical superconducting transition temperatures (Tc), of 260 K in LaH10, close to the commonly accepted threshold for room temperature, 293 K, at pressures near 180 GPa. We successfully synthesized a metallic La-based superhydride from La metal and ammonia borane, NH3BH3, and find a multi-step transition with a Tc of 294 K for the highest onset. When subjected to subsequent thermal excursions to higher temperatures that promoted a chemical reaction to what we believe is a ternary or higher order system, the transition temperature was driven to higher temperatures. Although the reaction does not appear to be complete, the onset temperature was pushed from 294 K to 556 K before the experiments had to be terminated. The results provide evidence for hot superconductivity well above room temperature, in line with recent predictions for a higher order hydride under pressure.

arXiv comment30 pages including 6 figures ( with 2 side by side figures)

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Cited by in corpus (14)

• In-silico synthesis of lowest-pressure high-$T_{\text{c}}$ ternary superhydrides
• Effect of paramagnetic impurities on superconductivity in polyhydrides: $\text{s}$-wave order parameter in Nd-doped LaH${}_{10}$
• First-principles study on the electronic structure of Pb${}_{10-x}$Cu${}_x$(PO${}_4$)${}_6$O ($x$=0, 1)
• Metal Borohydrides as high-$T_c$ ambient pressure superconductors
• On parent structures of near-ambient nitrogen-doped lutetium hydride superconductor
• Evidence against superconductivity in flux trapping experiments on hydrides under high pressure & On magnetic field screening and expulsion in hydride superconductors
• Quantum lattice dynamics and their importance in ternary superhydride clathrates
• Synthesis of possible room temperature superconductor LK-99:Pb${}_9$Cu(PO${}_4$)${}_6$O
• Hydrogen in superconductors
• Percolation-induced resistivity drop in cold-pressed LuH2
• Investigations of pressurized Lu-N-H materials by using the hybrid functional
• Transmission of radio-frequency waves and nuclear magnetic resonance in lanthanum superhydrides
• Reply to "Comment on `Nonstandard superconductivity or no superconductivity in hydrides under high pressure' "
• Hydride superconductivity: here to stay, or to lead astray and soon go away?