The structural and optical behavior of Ag+ and Gd3+ ions in CdWO4

In this research, Cadmium tungstate (CdWO4 or CWO), CWO: Gd, CWO: Ag, Ag and Gd-doped CWO (co-doped CWO) nanopowders were synthesized by using a simple chemical method. In addition, their microstructure and optical properties were characterized by applying different techniques. For example, XRD patterns revealed the purity of the synthetic nanopowders, and XPS results showed the Cd, W, O, Ag, and Gd characteristic peaks in the nanopowders. Further, the SEM and TEM images indicated that the size of the nanoparticles is distributed over the range of 24 to 63 nm. The shape and size of the nanoparticles in co-doped CWO were nanorod and reduced by half. Furthermore, UV-Vis spectra indicated that their bandgap energies vary from 5.3 to 5.55 eV. The PL and IBIL spectra exhibited light emission in the blue-green range at 468 and 495nm, respectively, at room temperature. The excited electrons in the 1T1u level of the WO66- complex were trapped in the 6IJ level of Gd3+ by cross-relaxation. The plasmonic effect of Ag+ ions and fluorescence resonance energy transfer (FRET) to the energy level of 3T1u increased the total intensity in the PL and IBIL spectra. Synthesized nanopowders are proper alternatives to fluorescent single crystals and produce nanocomposite flexible scintillators for ionizing radiation detection.