Effect of Doping Concentration and Excitation Power on Upconversion and Temperature Sensitivity of Gd3Ga5O12:Yb3+/Er3+ Phosphors

Abstract

Yb/Er codoped Gd3Ga5O12 nanocrystalline upconverting phosphors were produced by the sol-gel pechini method at 1000 °C annealing temperature. The phosphor structure, morphological features, and luminescent properties of the fabricated material were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), and photoluminescence measurements (PL). Upconversion luminescence characteristics were investigated in the range of 450-850 nm by a 975 nm laser source. Emission, optical, and theoretical thermal behaviors were analyzed with respect to Er3+ ion content and the increasing excitation power. Temperature sensitivity calculations based on the fluorescence intensity ratio were performed by employing the thermally-coupled levels of Er3+. The maximum sensitivity was calculated with the optimal value of 0.83x10-2 K-1 for Gd3Ga5O12:2%Yb3+,0.5%Er3+ nanophosphor. The results pointed out that Yb/Er codoped Gd3Ga5O12 may be a potential candidate for optical temperature sensors and lighting.