White light-emitting properties of NaGdF4 nanotubes through Tb3+, Eu3+ doping

White light-emitting NaGdF4 phosphor samples based on efficient energy transfer between Tb3+ and Eu3+ were synthesized via a conventional hydrothermal reaction process. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra and lifetime measurement were performed to characterize the samples. The energy transfer process between Tb3+ and Eu3+ was demonstrated to be a resonant type via a dipole-dipole interaction mechanism. Furthermore, for NaGdF4: Tb3+, Eu3+, white light emission can be realized in the single-phase NaGdF4 host by reasonably adjusting the relative doping concentrations of Tb3+ and Eu3+ under ultraviolet excitation. Due to their excellent PL properties and good CIE chromaticity coordinates, the as-prepared Tb3+, Eu3+ co-doped NaGdF4 nanocrystalline phosphors have potential application in field-emitting displays.