Room-temperature X-ray induced photochromic properties of tungsten oxide

The transformation of tungsten oxide from yellow (without X-ray) to blue green (60 min) under X-ray radiation of varying duration, and it is a continuous process. Under X-ray irradiation treatment, some of the W-O bonds break, causing the oxygen molecules to leave the surface lattice and creating oxygen vacancies. One oxygen vacancy in WO3 generally causes two electrons, which reduces W6+ ions into W5+. The product is HxWO3, resulting in a reduction in the crystalline volume and band gap of the sample. Simultaneously thermally annealed pre- and post-X-ray irradiation samples, both of which are the same color after cooling. This new finding extends the photochromic energy range of tungsten oxide and has important implications for the design and fabrication of other X-ray-induced photochromic materials for charge transfer, which will certainly benefit the development of next-generation X-ray detection materials.