High-Temperature Superconducting Phase in Clathrate Calcium Hydride CaH6 up to 215 K at a Pressure of 172 GPa

Electron–phonon coupling and superconductivity in an alkaline earth hydride CaH6 at high pressures

“…It is thus likely that at pressures higher than P c , the Im3m phase of CaH 6 exhibits a decrease in T c with increasing pressure, consistent with the previous [31] and present DFT calculations. However, the structure of CaH 6 at lower pressures below ∼170 GPa was not identified in experiment [32], where the x-ray diffraction (XRD) data exhibited several unidentified peaks arising from the unknown phases, indicating that the synthesized samples reflect the presence of disorder with mixed phases. The XRD measurements for high quality samples are demanded in the future to identify the structures of calcium superphydirdes as a function of pressure.…”

“…As another kind of high-T c hydride having a H clathrate structure, the alkaline earth metal superhydride CaH 6 with the high crystalline symmetry of space group Im3m (see figure 1(a)) was theoretically predicted to exhibit a T c of 235 K at 150 GPa [31]. To verify this prediction, Yanming Ma and his co-workers [32] have recently synthesized CaH 6 by a laser heated DAC technique and measured a maximum T c of 215 K at 172 GPa. Such an experimental confirmation of the high T c over 200 K in CaH 6 extends the realm to search for room-temperature superconductors in non-rare earth metal superhydrides.…”

Pressure-induced high-temperature superconductivity in ternary Y–Zr–H compounds

“…6 Until now, almost all binary hydrides have been intensively studied in theory and a considerable number have been experimentally confirmed. For example, covalent hydride H 3 S and clathrate hydrides CaH 6 , YH 6 and LaH 10 7–20 have been synthesized above 150 GPa and exhibit superconducting transition temperatures above 200 K.…”

Emergent superconductivity in K2ReH9 under pressure

“…Thereinto, some of clathrate hydrides have been verified in experiments ( e.g. , LaH 10 , 16,17 YH 6 , 18,19 YH 9 , 23 and CaH 6 24,25 ).…”