XANES and XEOL studies of Eu-doped calcium tungstate in silica synthesized by sol-gel method

Europium-doped calcium tungstate (CaWO4:Eu) was synthesized by a modified Pechini method. X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) was employed to probe the chemical and luminescence properties of CaWO4:Eu. XANES results demonstrate that the chemical environment around calcium in the doped CaWO4 is similar to that of undoped CaWO4. On the other hand, chemical environment around oxygen is very different. Moreover, the results suggest that contributions to luminescence in the sample are from both silica (from silica matrix) and CaWO4. Using XEOL, luminescence pathways and efficiency associated with the system can be identified.