Pressure‐induced Changes of the Crystal Structure of Eu4P3

Pressure‐induced structural changes and electronic properties of rhombohedral Eu₄P₃ were characterised by means of X‐ray powder diffraction and X‐ray absorption spectroscopy at the Eu L_III threshold. The measurements at low pressures indicate oxidation states of the europium atoms which are compatible with a composition Eu₃²⁺Eu³⁺P₃. At a pressure of 8(1) GPa, Eu₄P₃ undergoes a structural phase transition. The cubic high pressure modification with (anti‐)Th₃P₄ type crystal structure is also identified as a compound with a non‐integer average oxidation state of the europium atoms.