Preparation and luminescence properties investigation of Eu3+, Tb3+-doped LaNbO4:RE3+ (RE = Eu, Eu/Tb, Tb)

In this work, doped and co-doped LaNbO 4 :RE 3+ (RE = Eu, Eu/Tb, Tb) single crystals were prepared by a unique hydrothermal method under the condition of supercritical water and a wide temperature range (823–923 K). The crystal structure of LaNbO 4 :Eu 3+ /Tb 3+ were refined by virtue of the Rietveld method, which can determine the occupation position of dopants. The luminescence properties of Eu 3+ /Tb 3+ -doped LaNbO 4 phosphors were carefully measured and analyzed by diffuse reflectance spectra and ultraviolet. The energy transfer was recognized between host and doped Eu 3+ /Tb 3+ ions based on the luminescence spectra and decay lifetimes, which is dominated by electric multipolar interaction. The results show that the strong emission peaks at 491 nm ( 5 D 4 – 7 F 6 ), 550 nm ( 5 D 4 – 7 F 5 ), 590 nm ( 5 D 4 – 7 F 4 ), 623 nm ( 5 D 4 – 7 F 3 ) can be observed at the optimum reaction temperature of 650 °C, corresponding to CIE coordinates (0.3398, 0.3288). By adjusting the concentration of Eu 3+ /Tb 3+ ions, the emission colors of LaNbO 4 :Eu 3+ /Tb 3+ are varied from blue to pink and to white. Consequently, the synthesis strategy reported herein not only holds extensive promise for expanding the preparation techniques of materials with good luminescence properties but also promotes the practical applications of LaNbO 4 single crystal in low color temperature and high index white light-emitting diode (WLED).