Synthesis of superconducting phase of La0.5Ce0.5H10at high pressures.

ABSTRACT

Clathrate hydrideFm3-m-LaH10has been proven as the most extraordinary superconductor with the critical temperatureTcabove 250 K upon compression of hundreds of GPa in recent years. A general hope is to reduce the stabilization pressure and maintain the highTcvalue of the specific phase in LaH10. However, strong structural instability distortsFm3-mstructure and leads to a rapid decrease ofTcat low pressures. Here, we investigate the phase stability and superconducting behaviors ofFm3-m-LaH10with 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 11. X-ray diffraction and Raman scattering measurements reveal the stabilization ofFm3-m-La0.5Ce0.5H10in the pressure range of 140-160 GPa. Superconductivity withTcof 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.