Lanthanum decahydride is a polyhydride or superhydride compound of lanthanum and hydrogen (LaH₁₀) that has shown evidence of being a high-temperature superconductor. It was the first metal superhydride to be theoretically predicted, ^{[2] [3]} synthesized, ^[4] and experimentally confirmed ^[5] to superconduct at near room-temperatures. It has a superconducting transition temperature T_C around 250 K (−23 °C; −10 °F) at a pressure of 150 gigapascals (22×10^⁶ psi), and its synthesis required pressures above approximately 160 gigapascals (23×10^⁶ psi). ^{[6] [7]}

Synopsis

Since its discovery, ^[8] the superconducting properties of LaH₁₀ and other lanthanum-based superhydrides have been experimentally confirmed in multiple independent experiments. ^{[9] [10] [11] [12]} The compound exhibits a Meissner effect below the superconducting transition temperature. ^[13] A cubic form can be synthesized at 1,000 K (730 °C; 1,340 °F), ^[6] and a hexagonal crystal structure can be formed at room temperature. ^[14] Further reports indicate T_c is increased with nitrogen doping, ^[15] and decreased with the introduction of magnetic impurities. ^[16]

The cubic form has each lanthanum atom surrounded by 32 hydrogen atoms, which form the vertices of an 18-faced shape called a chamfered cube. ^[17]

A similar compound, lanthanum boron octahydride, was computationally predicted to be a superconductor at 126 K (−147 °C; −233 °F) and pressure 50 gigapascals (7.3×10^⁶ psi). ^[18]

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