Improved luminescence of CaWO4:Eu3+ microspheres by codoping Gd3+

• The successful synthesis of CaWO4:Eu3+/Gd3+ microspheres.
• The morphology control of CaWO4:Eu3+/Gd3+ microspheres through the trisodium citrate.
• The improved luminescence by codoping Gd3+ ions.

CaWO4:Eu3+/Gd3+ samples have been synthesized through a hydrothermal process with the assistant of trisodium citrate. The phase and morphology of samples have been characterized by XRD, FTIR, SEM and TEM. The XRD results indicate that the samples have the pure scheelite phase. The SEM and TEM images show that the samples are microspheres containing lots of nanoparticles. The luminescent properties of CaWO4:Eu3+/Gd3+ samples also have been measured. Under the excitation at 278 nm, CaWO4:Eu3+/Gd3+ samples show characteristic emission bands originating from the 5D0 → 7Fj (j = 1, 2, 3 and 4) transitions of Eu3+ ions. The codoping Gd3+ ions can improve the emission intensity highly. Also, the samples show good thermal stability.