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

Abstract

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.