Growth and Optical Spectra of Tb3+/Eu3+ Co-doped Cubic NaYF4 Single Crystal for White Light Emitting Diode

High quality Tb3+/Eu3+ co-doped cubic NaYF4 single crystal in the size of Φ1.0 cm × 6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF–YF3 system under the condition of completely closed Pt crucible. A white light emission from the combination of the violet-blue, blue, green, orange, and red lights with chromaticity coordinates of x = 0.3107, y = 0.3274, correlated color temperature of Tc = 6637 K, color rendering index of Ra = 83, and color quality scale of Qa = 82 could be obtained from 1.51 mol% Tb3+ and 1.42 mol% Eu3+ co-doped cubic NaYF4 single crystal when being excited by a 369 nm light. This indicates that Tb3+/Eu3+ co-doped cubic NaYF4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.