Tunable emission and concentration quenching of Tb3+ in magnesium phosphate lithium.

Tunable photoluminescence of Tb 3+ -doped LiMgPO 4 (Tb 3+ :LiMgPO 4 ) phosphors with different Tb 3+ concentrations are successfully synthesized by a high temperature solid-state reaction routine. X-ray diffraction (XRD) and photoluminescent spectroscope (PLS) are employed to characterize the phosphors. It is found that a suitable firing temperature is important for the synthesis of the phosphors, and pure phase material can only be obtained around 900 °C. PL spectra reveals typical 5 D 4 to 7 F j energy transition of Tb 3+ ions, and the emission colors varied from red to green with Tb 3+ concentration increasing, which is caused by the concentration quenching of Tb 3+ emission centers in the LiMgPO 4 matrix. The emissions peaking at 591, 619 and 695 nm are quenched at concentration of 1.5%, while the emissions at 489 nm and 543 nm are quenched at concentration of 8%. Further analysis of the data reveals two different energy transfer mechanisms for the five emission bands. The dipole–dipole model is proposed for the energy transfer of the red bands peaking at 694 nm, 619 nm and 591 nm, while the exchange interaction model is suggested for that of the green bands (543 nm and 489 nm), due to the different ion separations caused by different Tb concentrations. [ABSTRACT FROM AUTHOR]