Upconversion luminescence and temperature sensing performance of Zn2+-doped Ba2GdAlO5: Yb3+, Er3+ phosphors

Although upconversion luminescence (UCL) materials have attracted considerable attention in biomedical, lighting, anti-counterfeiting, and solar cells due to their excellent fluorescence properties, reports of the dibarium gadolinium aluminum oxide (Ba 2 GdAlO 5 ) are scarce. Herein, we synthesized the single-phase Ba 2 GdAlO 5 material with non-stoichiometric Ba 2 Gd 1.06 Al 0.94 O 5 (denoted as BGAO, hereafter). The X-ray Rietveld refinement reveals that the substitution of Gd for Al accounts for the non-stoichiometry. Notably, the UCL properties of BGAO are realized by doping with Yb 3+ and Er 3+ ion pair, and it can be further enhanced significantly by co-doping with appropriate Zn 2+ ions. The SEM images show that the particle size increases as the concentration of Zn 2+ ions increases. The X-ray Rietveld refinement results of the Zn-doped BGAO: 0.1 Yb 3+ , 0.03Er 3+ phosphor indicate the substitution of Zn 2+ for Ba 2+ and Al 3+ ions simultaneously. Grain growth and lattice distortion account for the improvement of UCL properties after Zn 2+ ions doping. In addition, the temperature sensing performance of the Zn 2+ -doped sample has been researched based on the fluorescence intensity ratio (FIR) technique, and the maximum absolute and relative sensitivities ( S A-max and S R-max ) are obtained to be 4.8 × 10 −3  K −1  at 498 K and 1.1% K −1 at 298 K, respectively. This work provides a candidate with high UCL intensity for potential applications in optical temperature sensors.