Single Crystal X-Ray Diffraction Investigation of the Heterogenous High Tc La-H Mixtures

Recent experiments have demonstrated an astonishing close-to room temperature superconductivity (~ 250 K) in laser-heated La-H mixtures between 135 GPa and 200 GPa. While the predicted LaH10 phase with a high superconducting temperature (Tc) was reported to have been observed, both resistivity and powder X-ray diffraction measurements reveal highly inhomogeneous samples with numerous unknown phases. To properly understand the high Tc detected in La-H samples, it is vital to structurally identify all phases present. The here proposed investigation aims at unambiguously solving the crystal structure of all crystalline solids observed in laser-heated La-H mixtures between 135 GPa and 180 GPa by employing the submicronic and high intensity X-ray beam of ID11 to perform single crystal X-ray diffraction on the resulting polycrystalline La-H samples. This crucial investigation will enable the complete understanding of the ultra-high Tc measurements in La-H mixtures.