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

Tb/Euco-doped transparent glass ceramics containing CaFnanocrystals 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 Tbto Euof CaF:Tb,Euphosphors 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 Tbat 545 nm(~5D→~7F) to Euat 615 nm(~5D→~7F) was highly temperature-dependent with an approximate linear relationship, and the temperature sensitivity was about 0.4%/K. It is expected that the investigated Tb/Euco-doped CaFglass ceramics may have prospective application in optical thermometry.