Keywords: 
• 超导电性 /
• 电声耦合 /
• 第一性原理计算

Abstract: Raising superconducting transition temperature (Tc) is an important task of fun-damental research on superconductivity. It is also a prerequisite for the large scale application of superconductors. Since the microscopic mechanism of high-Tc superconductivity is unknown, the conventional approach for increasing Tc is either to apply high pressure to a material which has the potential to become superconducting, or to push it close to an antiferromagnetic or some other quantum instability point by chemical doping. In this article, the authors point out that another general approach for raising Tc is to lift theσ-bonding bands to the Fermi level, or to metalize theσ-bonding elections. This approach can increase the probability of finding a novel high-Tc super-conductor because the coupling ofσ-bonding electrons with phonons is generally strong and the superconducting transition induced by this interaction can occur at relatively high temperatures. After elucidating the underlying mechanism, the authors discuss a number of schemes to metalizeσ-bonding electrons, and present their recent prediction for the crystalline and electronic struc-tures of two potential high-Tc superconductors, Li2B3C and Li3B4C2, with Tc higher than 50 K.