Up‐conversion and temperature sensing properties of Na2GdMg2(VO4)3:Yb3+,Er3+ phosphors

In this paper, Na2GdMg2(VO4)3:Yb3+,Er3+ phosphors were synthesized through high‐temperature solid‐state method. According to X‐ray powder diffractogram, diffuse reflection spectra, scanning electron microscopy, up‐conversion (UC) emission spectra, power‐dependent UC spectra, fluorescent lifetime curves, and temperature‐dependent emission spectra, the crystal structures, UC luminescent characteristics, and the performances of temperature sensing by using fluorescence intensity ratio technique were studied in detail. Heavy‐doped phosphors with 59% (Yb3+ and Er3+) doping content are achieved. In addition, excited by 980nm laser, three characteristic luminescence peaks of Er3+ at 525 nm (2H11/2 → 4I15/2), 550 nm (4S3/2 → 4I15/2) and 660 nm (4F9/2 → 4I15/2) emerge in the UC spectra of Er3+ single‐doped and Yb3+,Er3+ co‐doped phosphors. UC spectra are dominated by green emission and greatly enhanced UC emission over 389 times is realized by introducing Yb3+. In addition, the ratiometric techniques of thermally coupled energy levels of Er3+ (525/550 nm, 2H11/2/4S3/2 → 4I15/2) are used to achieve a wide range of temperature measurement. When the temperature is 303 K, relative sensitivity is as high as 0.976%K–1. The minimal temperature resolution is 0.3 K@303 K. All experimental results show Yb3+,Er3+ co‐doped Na2GdMg2(VO4)3 phosphors might act as optical temperature sensing materials.