Re-dispersible CaWO4:Tb3+ nanoparticles: Synthesis, characterization and photoluminescence studies

Nanoparticles of CaWO4 doped with Tb3+ were synthesized in ethylene glycol, DMSO, water and mixed solvents at a very low temperature. XRD patterns showed that the nanoparticles prepared in all these solvents have a scheelite-type tetragonal structure without the presence of deleterious phases. The photoluminescence (PL) spectra of Tb3+ doped CaWO4 (EG) nanoparticles doped with different Tb3+ concentrations under 243 nm excitation show the characteristic green emission (545 nm) of Tb3+ corresponding to 5D4→7F5 transition due to efficient charge transfer from WO42− to Tb3+. Other emissions can be observed due to 5D4→7F6,4,3 transitions. The optimum concentration of Tb3+ for the highest luminescence was found to be 10 at%. The luminescence intensity of the samples prepared in EG:water (1:1) is more than that in EG, DMSO and other mixed solvents. As-prepared samples are well dispersed in polar solvents like methanol, ethanol and water and will be useful in biological applications.