Record BCS high temperature superconductivity in B-doped Q-carbon

Abstract

We have created new B-doped Q-carbon phases having 33 at% (QB33) and 50 at% (QB50) boron, which show record BCS superconducting transition temperature of 112 and 164 K, respectively, at ambient pressure. Nanostructuring enhanced transition temperatures for QB33 and QB50 to 120 and 187 K, respectively. These phases were synthesized by nanosecond pulsed laser melting and quenching of B and C layers. QB33 is formed when the central C atoms in two of the three tetrahedra are replaced by B atoms and these three-unit tetrahedra are packed randomly. For QB50 phase, central C atoms in every tetrahedra are replaced by B atoms.