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GdPO 4 :Eu 3+ nanorods (~20 nm) were synthesized by a facile hydrothermal technique based on the water/2-PrOH interface. The size of nanorods was controlled by varying the reaction temperature and solvent interface. After calcination at 700 °C, the hexagonal phase of as-prepared GdPO 4 ·H 2 O:Eu 3+ nanorods was transformed into the monoclinic phase, which was confirmed by XRD patterns and TEM images. During the calcination process, along with the phase transformation, the size of nanorods was also shortened by the removal of H 2 O molecules from the lattice. Photoluminescence (PL) excitation spectra revealed the efficient energy transfer between Gd 3+ and Eu 3+ ions and the orange-red emission was typically observed from PL spectra because the Eu 3+ ions exist with inversion symmetry in the lattice. Also, these GdPO 4 :Eu 3+ nanorods were highly dispersible in water. [ABSTRACT FROM AUTHOR]

Tm3+/Er3+/Eu3+/Er3+, Tm3+/Er3+/Eu3+ single, double and triple activator ion/ions doped nanocrystalline BaGd2O4 (BG) phosphors were prepared by a Pechini type sol-gel process. After annealing at 1300 °C, X-ray diffraction patterns confirmed their orthorhombic structure. Field-emission transmission electron microscope images of the BG sample indicated a nanoneedle-type morphology. Photoluminescence (PL) and cathodoluminescence (CL) measurements were utilized to establish the emission properties of rare-earth ions doped nanocrystalline BG host lattice. Under near-ultraviolet (NUV) excitations, BG:Tm3+ and BG:Er3+ exhibited their characteristic emissions in the blue and green regions, respectively, while BG:Tm3+/Er3+ and BG:Tm3+/Er3+/Eu3+ showed cyan and white light emissions, respectively, when doped with appropriate amounts of activator ions. In the PL, the cross-relaxation process is dominant rather than the energy transfer process. Due to the different mechanism from PL, the CL spectra showed different emission features of BG: Tm3+/Er3+/Eu3+ phosphor. The CL spectra of BG:Tm3+ and BG:Er3+ established the high purity blue and green emissions, respectively. From the PL and CL investigations, the white-light emission was realized from the single-phase BG:Tm3+/Er3+/Eu3+ phosphor under NUV and low voltage electron beam excitations. [ABSTRACT FROM AUTHOR]