Studies on Rare-Earth Co-Doped: Calcium Tungstate Nano-Crystals

Abstract

Abstract: We report the synthesis of co-doped Calcium tungstate (CaWO4) nano-crystals with Gadolinium (Gd) and Neodymium (Nd) rare earth ions by hydrothermal synthesis method for the first time. The synthesized nano-crystals were characterized by Xray diffraction (XRD) with energy dispersive analysis of the X-rays (EDAX) and Field-emission scanning electron microscopy (FESEM), and photo-luminescence excitation studies. The phase of the nano-crystals under study was identified by X-ray diffraction (XRD). The Field-Emission Scanning Electron Microscope (FESEM) image shows that the synthesized nano-crystals are in the size range of 51nm – 80nm. The presence of Gd and Nd rare earth ions in the GD-Nd co-doped CaWO4 nano-crystals was confirmed by the energy dispersive analysis of the X-rays (EDAX). The photoluminescence properties of the Gd-Nd co-doped CaWO4 nano-crystals were compared with the undoped CaWO4 nano-crystals and are reported. The synthesized nano-crystals exhibit emissions at (i) 369nm, 392nm, 435nm and 477nm for an excitation wavelength of 280 nm and (ii) 540nm and 669nm for an excitation wavelength of 490nm. The emission wavelengths clearly indicate the blue light and green light generation, which is significant for developing luminescent materials of tungstate systems.