High-Tcsuperconductivity in doped molecular superconductors ofK4B8-xMxH32(M = C, N) under high pressure.

Stabilized and metallic light elements hydrides have provided a potential route to achieve the goal of room-temperature superconductors at moderate or ambient pressures. Here, we have performed systematic DFT theoretical calculations to examine the effects of different light elements C and N atoms doped in cubic KBHhydrides on the superconductivity at low pressures. As a result of various atoms substituting, we have found that metallic KB_{8-x}MH(M = C, N) hydrides are dynamically stable at 50 GPa, band structures and density of states (DOS) indicate that sizeableTccorrelates with a high B-H DOS at the Fermi level. With the increasing of B atoms in KB_{8-x}MHhydrides, the DOS values at Fermi level have been improved due to the delocalized electrons in B-H bonds, which result in strong electron-phonon coupling (EPC) interaction and increase theTcfrom 19.04 to 77.07 K for KCHand KBHat 50 GPa. The NHunit in stable KBNHhydrides has weakened the EPC and led to lowTcvalue of 21.47 K. Our results suggest the light elements hydrides KBHand KBCHcould estimate highTcvalues at 50 GPa, and the boron hydrides would be potential candidates to design or modulate hydrides superconductors with highTcat moderate or ambient pressures.