Enhancement of thermal stability and reliability of green LuAG phosphors by appropriate Y substitution

Green Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphors were prepared by conventional solid-state reaction. The influence of Y concentration on the photoluminescence (PL), thermal stability and reliability properties of the phosphors were studied. The PL emission bands of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce showed red shift from 520 to 540 nm with increasing Y content (x value) under excited at 450 nm. As the temperature increases from 298 to 473 K, the PL intensity of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphor decreases by 21.72, 11.10, 5.45, 9.01 and 16.30% with x value is 0, 0.2, 0.4, 0.6 and 0.8, respectively. The thermal cycling testing results show that the relative PL intensity of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphor decrease to 86.97, 91.94, 97.22, 95.69 and 92.75% with x value is 0, 0.2, 0.4, 0.6 and 0.8 after storing the phosphors into an ambient condition of 120 °C for 1 h and −40 °C for 1 h by turns for five times. Reliability test results show that the relative PL intensity of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphor decrease to 90.76, 95.17, 96.54, 93.37 and 91.12% with x value is 0, 0.2, 0.4, 0.6 and 0.8 after the ambient condition of 85 °C/RH 85% for the exposure time of 336 h; The relative PL intensity of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphor decrease to 88.63, 94.24, 95.74, 92.60 and 86.95% with x value is 0, 0.2, 0.4, 0.6 and 0.8 after soaking into boiled water for 3 h. It can be summarized that the appropriate addition of Y could enhance both the thermal stability and reliability of Lu_2.94−xY_xAl₅O₁₂: 0.06Ce phosphors remarkably.