Extremely intense green up-conversion luminescent and ultra-high temperature sensitivity in Er3+/Yb3+ co-doped BiTa7O19 phosphors

Er3+/Yb3+ co-doped BiTa7O19 phosphors with bright pure green emission were synthesized first by a solid-state reaction method. The lattice structure and morphology of the synthesized samples was determined by X-ray diffraction (XRD) and field emission scan electronic microscope (FESEM). These samples' up-conversion luminescence (UCL) and optical temperature sensing behavior were investigated by photoluminescence spectroscopy under 980 nm laser diode (LD) excitation. The optimum values of Er3+ and Yb3+ doping concentration were 10 mol % and 40 mol %, respectively. Further optimizing the preparation process of (Bi0.5Er0.1Yb0.4)Ta7O19, the green UCL integrated intensity of (Bi0.5Er0.1Yb0.4)Ta7O19 is up to 1.32 times than that of commercial NaYF4: Er3+/Yb3+ phosphors under 980 nm LD 35.71 W/cm(2) excitation. In addition, all Er3+/Yb3+ co-doped BiTa7O19 phosphors have a good green monochromaticity (S-gr), and the S-gr reached 0.98-0.99. Based on the fluorescence intensity ratio (FIR) of the transition emission of the thermally coupled H-2(11/2) and S-4(3/2) levels to the ground state, the maximum absolute sensitivity (S-A) of optimized (Bi0.5Er0.1Yb0.4)Ta7O19 is calculated as high as 0.01624 K-1 at 475 K, which is much higher than other reported materials. These results indicate that BiTa7O19: Er3+/Yb3+ may have potential applications in biological imaging, fluorescent labels, and optical temperature sensors.

Automated summary

Er3+/Yb3+ co-doped BiTa7O19 phosphors with bright pure green emission were successfully synthesized in this study. The optimized doping concentration resulted in higher green luminescence intensity compared to commercial phosphors, as well as a higher absolute sensitivity.