Efficient sensitization of Tb3+ emission by Dy3+ in CaMoO4 phosphors: Energy transfer, tunable emission and optical thermometry

Dy3+/Tb3+ codoped CaMoO4 phosphors were synthesized by a simple sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy. The energy transfer process of Dy3+→Tb3+ was confirmed by excitation and emission spectra and luminescence decay curves, and the energy transfer efficiency was also estimated. The results verified that the efficient emission of Tb3+ was sensitized by Dy3+ under the excitation of 354 nm, realizing tunable emission in CaMoO4 phosphors. Furthermore, optical thermometry was achieved by the fluorescence intensity ratio between Tb3+: 5D4→7F5 (~546 nm) and Dy3+: 4F9/2→6H13/2 (~575 nm). It is expected that the investigated CaMoO4 nanograins doped with Dy3+/Tb3+ have prospective applications in display technology and optical thermometry.