Pressure-Enhanced Superconductivity and Structural Phase Transition in Layered Sn4P3

High pressure provides a unique tuning method depending on structure modulation to explore the structure–property relationship. Herein, the pressure-induced structural phase transformation and enhanced superconductivity in a layered binary phosphide Sn₄P₃ are reported. Comprehensive measurements using in situ synchrotron X-Ray diffraction and Raman spectroscopy reveal a structural phase transition with mild distortion of SnP₃ building blocks and interlayer shrinkage under high pressure. This differs from a conventional trigonal SnAs(P)₃ to square SnAs(P)₄ topotactic transition in SnAs(P)-based compound. Through this structure reconstruction under high pressure, electron distribution has been reorganized and phonons have softened, facilitating a high superconducting temperature (T_c) value of 7.8 K at 34.9 GPa, which is almost six times higher than its ambient value. The study introduces a new transition route in layered SnAs/SnP-based intermetallic materials and provides insight into the structural and electronic changes under high pressure for Sn₄P₃.