Energy Transfer and Colorful Emission of Eu3+- and Tb3+-Co-Doped CaWO4 Phosphors

Eu3+/Tb3+-co-doped CaWO4 phosphors were synthesized by a simple green co-precipitation process. The structure of the samples was investigated by X-ray diffraction. The photoluminescence spectra and fluorescence decay lifetimes of the samples were measured to investigate the luminescence properties. We analyzed the energy transfer process between Eu3+- and Tb3+-doped CaWO4. As the Tb3+ to Eu3+ energy transfer process was confirmed, Eu3+- and Tb3+-co-doped CaWO4 phosphors showed a color-tunable emission from green to red under a 365-nm UV lamp.