Structural characterization and temperature-dependent luminescence of CaF2:Tb3+/Eu3+ glass ceramics

Tb3+/Eu3+ co-doped transparent glass ceramics containing CaF2 nanocrystals were successfully synthesized by high temperature melt-quenching method and subsequent heating. The structure and morphology of the samples were investigated by X-ray diffraction (XRD), transmittance electron microscopy (TEM), high resolution TEM (HRTEM) and selected area electron diffraction (SAED). The photoluminescence properties and energy transfer process from Tb3+ to Eu3+ of CaF2:Tb3+,Eu3+ phosphors were also investigated through excitation spectra and decay curves. In addition, the emission spectra of the glass ceramics in a wide temperature range from 21 to 320 K were recorded under the excitation of 485 nm. It was found that the fluorescence intensity ratios of Tb3+ at 545 nm (D-5(4)-> F-7(5)) to Eu3+ at 615 nm (D-5(0)-> F-7(2)) was highly temperature-dependent with an approximate linear relationship, and the temperature sensitivity was about 0.4%/K. It is expected that the investigated Tb3+/Eu3+ co-doped CaF2 glass ceramics may have prospective application in optical thermometry.