화학공학소재연구정보센터
Journal of the American Ceramic Society, Vol.101, No.7, 3076-3085, 2018
Tunable emission color of Li2SrSiO4:Tb3+ due to cross-relaxation process and optical thermometry investigation
A series of Li2SrSiO4:xTb(3+) (0.2%, 0.4%, 0.6%, 0.8%, 2%, 4%, and 6%) phosphors were prepared by conventional solid-state reaction. It was found that this silicate phosphor has a wide excitation band at near-ultraviolet region (230-300nm) due to spin-allowed 4f(8)4f(7)5d(1) transitions of Tb3+ ions, with the exact position dependent on the crystal field of the lattice. The cross-relaxation process originating from (D3D4)-D-5-D-5 and (F6F0)-F-7-F-7 happened between different Tb3+ ions. It leads to the luminescence color of Li2SrSiO4: xTb(3+) tuning from blue to green just by controlling Tb3+ concentrations. Furthermore, concentration quenching mechanism, energy migration type, cross-relaxation rate and efficiency, are discussed in detail. Finally, optical thermometry properties were investigated via temperature-dependent emission spectra. The results show that low-concentration-doped sample (Li2SrSiO4:0.4%Tb3+) shows remarkable optical thermometry based on fluorescence intensity ratio (FIR) between the blue and green emission of Tb3+ ions, whereas the high-concentration-doped sample (Li2SrSiO4:4%Tb3+) demonstrates small emission intensity loss. It illustrates that terbium-doped silicate phosphor is a multifunctional material with potential application for display field and optical thermometry.