Superconductivity at 253 K in lanthanum–yttrium ternary hydrides

Here we report the high-pressure synthesis of a series of lanthanum–yttrium ternary hydrides obtained at pressures of 170–196 GPa via the laser heating of P63/mmc La–Y alloys with ammonia borane. As a result, we discovered several novel compounds: cubic hexahydride (La,Y)H6 and decahydrides (La,Y)H10 with a maximum critical temperature TC ∼ 253 K and an extrapolated upper critical magnetic field BC2(0) of up to 135 T at 183 GPa. The...