Synthesis of superconducting phase of La<sub>0.5</sub>Ce<sub>0.5</sub>H<sub>10</sub> at high pressures
Ge Huang, Di Peng, T. Luo, Liu-Cheng Chen, Philip Dalladay‐Simpson, Zi-Yu Cao, Federico A. Gorelli, Guo‐Hua Zhong, Hai-Qing Lin, Xiao‐Jia Chen
Abstract
Abstract Clathrate hydride <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo>ˉ</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -LaH 10 has been proven as the most extraordinary superconductor with the critical temperature T c above 250 K upon compression of hundreds of GPa in recent years. A general hope is to reduce the stabilization pressure and maintain the high T c value of the specific phase in LaH 10 . However, strong structural instability distorts <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo>ˉ</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> structure and leads to a rapid decrease of T c at low pressures. Here, we investigate the phase stability and superconducting behaviors of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo>ˉ</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -LaH 10 with enhanced chemical pre-compression through partly replacing La by Ce atoms from both experiments and calculations. For explicitly characterizing the synthesized hydride, we choose lanthanum-cerium alloy with stoichiometry composition of 1:1. X-ray diffraction and Raman scattering measurements reveal the stabilization of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover> <mml:mn>3</mml:mn> <mml:mo>ˉ</mml:mo> </mml:mover> <mml:mi>m</mml:mi> </mml:math> -La 0.5 Ce 0.5 H 10 in the pressure range of 140–160 GPa. Superconductivity with T c of 175 ± 2 K at 155 GPa is confirmed with the observation of the zero-resistivity state and supported by the theoretical calculations. These findings provide applicability in the future explorations for a large variety of hydrogen-rich hydrides.