Novel structures and superconductivities of calcium–lithium alloys at high pressures: A first-principles study

Exposing a material to high pressures can fundamentally influence its crystal and electronic structure, leading to the formation of new materials with unique physical and chemical properties. Here, we have conducted a systematic search for Ca–Li alloys by using a global minima search based on particle-swarm optimization algorithm in combination with density functional theory calculations. We predict that Calcium and Lithium with a high Ca composition CaLi, Ca2Li and Ca3Li exist, and a strikingly decomposition-combination-decomposition oscillating behavior with pressure is revealed. All predicted Ca–Li compounds are metallic and good electron–phonon superconductors with transition temperatures (Tc) of around 8–19 K. The superconductivity mainly originates from the low-energy Ca vibrations and the pressure dependence of Tc is dominated by the phonon softening/hardening. •Three high Ca compositions of CaLi, Ca2Li, and Ca3Li alloys have been predicted.•High superconducting temperatures were predicted for Ca–Li alloys at high pressures.•The origin of the superconductivity is revealed.•The superconducting temperature increases with increasing pressures for Fd-3m CaLi.•The Fd-3m phase of CaLi is a potential high-temperature superconductor.