Synchrotron insights into luminescence of Y2O3:RE (RE = Eu or Tb) as powders and composite films

Rare-earth (RE)-doped Y2O3 nanoparticles (NPs) have been extensively investigated due to their remarkable optical properties, particularly as scintillators. For applications as primary sensors in high-resolution X-ray detection systems or in other photonic uses such as panel displays, these materials must present controlled and homogeneous particle size distribution, be effectively dispersed within a suitable host matrix, and their optical response must be properly evaluated within the relevant excitation energy range. In this work, we present a comprehensive multi-analytical study, integrating synchrotron-based methods to characterize the structure, crystallite size, morphology, and band gap of Eu- and Tb-doped Y2O3 NPs; the thickness and homogeneity of polydimethylsiloxane (PDMS)-based composite films; the oxidation states and local symmetry of the dopants; and luminescent behavior of both Y2O3:RE powders and Y2O3:RE@PDMS composite films. Furthermore, their luminescence mechanisms under vacuum ultraviolet (VUV) and X-ray irradiation were systematically investigated. Advanced synchrotron X-ray microscopy was used to correlate the chemical composition with the optical performance of Y2O3:Tb@PDMS luminescent screens. The results demonstrate a simple and cost-effective PVA-assisted sol–gel synthesis route for producing Y2O3:RE nanopowders and highlight the potential of Y2O3:RE@PDMS composites as flexible, high-performance, and easily fabricated primary sensors for X-ray imaging or even for other photonic applications.