Photoluminescence studies of CdWO4:Sm3+ phosphor: Concentration and annealing effect

A series of CdWO4 doped with different concentrations of Sm3+ have been successfully prepared by the combination of co-precipitation method with annealing of the precipitate formed. The prepared samples were characterized by XRD, TEM, FT-IR, SAED, EDS and PL. XRD studies exhibited monoclinic wolframite structure of the prepared samples and the crystallinity was increased with the increase of annealing temperature upto 900° C without any structural changes. FT-IR studies indicated vibrational bands of metal cations bonds like Cd-O, W-O and Cd-O-W for the CdWO4:Sm3+ phosphors in the ranges from 400 to 900 cm−1. Photoluminescence studies showed characteristic emission lines of Sm3+ centers at 569, 608, 653 and 715 nm upon 279 nm UV light excitation. The observed most intense peak at 653 nm is due to the 4G5/2-6H9/2 transition. The optimum concentration of Sm3+ was found at 1 at.%. The photoluminescence intensity was increased with the increase of annealing temperature.