The effect of Tm3+ concentration on the structure and luminescence characteristics of LuAG single crystal

Abstract

The optical floating zone method was utilized to generate a series of single crystals (Lu1-xTmx)3Al5O12 (x = 0, 0.005, 0.010, 0.015, 0.020), abbreviated as x Tm: LuAG. The concentration of activated ions has a considerable impact on luminous material performance. Thus, this research focuses on the effect of Tm3+ concentration on the micro-structure and luminescent properties of lutetium aluminum garnet single crystals. According to XRD diffraction data processed using Rietveld refinement, the micro-structure of LuAG single crystals would be distorted by Tm3+ doping. When the concentration of Tm3+ is 0.015, the lattice symmetry is the lowest. Upon examining emission spectra of Tm: LuAG, emission peaks of Tm3+ ions were identified. Various strengths of emission peaks were seen within the range of 400 to 600 nm, with the peak at 449 nm exhibiting the highest intensity, accompanied by a phenomenon of energy level splitting at this wavelength. The luminescence intensity of Tm: LuAG single crystal reaches its highest point when the doping concentration is 0.015. As doping concentration surpasses 0.015, the luminescence intensity gradually reduces, which causes a concentration quenching event. The optimum doping concentration of the sample is 0.015. Blasse formula yields a critical distance of 20.80 Å in Tm: LuAG single crystals. The reason for concentration quenching in LuAG crystals is that the interaction between the electric dipole and the electric quadrupole of Tm3+ ions occurs. Furthermore, when the concentration of Tm3+ ions increases, the fluorescence lifetime decreases. Tm: LuAG single crystals have certain application potential in areas such as three-dimensional display and biological imaging.