Hard X-ray-Induced Oxygen Intercalation in WO ₃ under High Pressure

Hard X-ray irradiation of a mixture of KClO 4 and WO 3 under high pressure produces a gradual lattice expansion of WO 3 accompanied by an overall decrease in WO 3 diffraction peak FWHM’s, indicating irradiation-assisted defect relaxation and structural reordering rather than radiation damage. Combined X-ray diffraction (XRD) and Raman results suggest stabilization and possible intercalation of molecular O 2 (produced via KClO 4 + hν→KCl+2O 2 ) within the WO 3 lattice via weak host–guest interactions which remained after depressurization and release of the sample to ambient conditions. The results demonstrate that high-pressure conditions can stabilize novel intercalated compounds of the form O 2 ·WO 3, highlighting the tungsten–oxygen semiconductor system as a promising platform for irradiation-driven photochemistry, trapping of radicals such as O in the solid state, and functional material discovery.