Superconducting ScP4 with a novel phosphorus framework.

Pressure has become an irreplaceable tool in preparing new materials with interesting property. Theoretical calculations, especially combined with structural evolution algorithm, have played a powerful role in accelerating the finding of functional materials. Phosphorus (P) has the ability of forming diverse motifs in element solids and compounds, which are closely related to their physical property. Here we explore high-pressure phase diagram of binary Sc-P compounds with the aim of finding new materials through first-principles structural search calculations. Besides reappearing the known NaCl-type ScP, two P-rich chemical compositions (e.g., ScP4 and ScP2) are identified at high pressures. Interestingly, ScP4 contains a novel three-dimensional P framework composed of eight- and four-membered channels. A one-dimensional Sc chain is located in eight-membered channel. Electronic property calculations disclose that ScP4 is metallic and superconductive. Its superconducting transition temperature (Tc) increases with decreasing pressure, and is up to 11 K at 50 GPa. Pressure-dependent density of states at the Fermi level is mainly responsible for the change of Tc. Other pressure-induced Sc-P phases are also superconductive, but have a weak electron–phonon coupling in comparison with ScP4. [ABSTRACT FROM AUTHOR]