A series of Ca499（PO4）3F：1%Eu^3＋, 1%X （X = Li＋, Au3＋, and Bi3＋） nanoparticles are prepared using hydrothermal method, with an average size of 33-62 nm. We study the improved photoluminescence properties of Ca4.99（PO4）3F：1%Eu3＋ by co-doping with Li＋, Au3＋, and Bi3＋ ions, respectively, and the enhancement of the emission intensities of Eu3＋ is observed in these samples. The effects of Li＋ acting as a charge compensator, Au3＋ as a plasma surface sensitizer, and Bi3＋ as an energy conversion agent are discussed. The results show Ca4.99（PO4）3F：1%Eu3＋, 1%X nanoparticles are a promising candidate as a red component for near-ultraviolet light-emitting diodes.
Graphene-ZnO nanocomposites were synthesized successfully through a one-step solvothermal approach. The mor-phology, structure, and composition of the prepared nanocomposites were investigated by scanning electron microscopy （SEM）, transmission electron microscope （TEM）, laser micro Raman spectroscopy, and Fourier transform infra-red spec-troscopy （FT-IR）. The outcomes confirmed that this approach is comparatively steady, practicable, and operable compared with other reported methods. The electrochemical performance of the graphene-ZnO electrodes was analyzed through cyclic voltammetry, altering-current （AC） impedance, and chronopotentiometry tests. The graphene-ZnO electrodes exhib-ited an improved electrode performance with higher specific capacitance （115 F·g^-1 ）, higher electrochemical stability, and higher energy density than the graphene electrodes and most reported graphene-ZnO electrodes. Graphene-ZnO nanocom-posites have a steady reversible charge/discharge behavior, which makes them promising candidates for electrochemical capacitors （ECs）.
The Er^3＋/yb^3＋ co-doped transparent oxyfluoride glass-ceramics containing CaF2 nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy （TEM） images showed that CaF2 nano-crystals of 20-30 nm in diameter precipitated uniformly in the glass matrix. luminescence of Er^3＋ at 540 nm and 658 nm was observed in Comparing with the host glass, high efficiency upconversion the glass ceramics under the excitation of 980 nm. Moreover, the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er^3＋ and Yb^3＋ was convinced and the possible mechanism of Er^3＋ up-conversion was discussed.
A novel red-emitting phosphor, CaYA1307： Eu^3＋, Sm^3＋, is synthesized by a combustion method at a low temperature （850 ℃）, and the single phase of CaYA1307 is confirmed by powder X-ray diffraction measurements. The photoluminescence property results reveal that the red emission intensity of Eu^3＋ is strongly dependent on the Sm^3＋ concentration. Only the Eu^3＋ luminescence is detected in the Eu^3＋-Sm^3＋ co-doped CaYA1307 phosphor with 393 nm excitation. However, under the characteristic excitation （402 nm） of Sm^3＋, not only the Sm^3＋ emission but also the Eu^3＋ emission are observed. A possible mechanism of the energy transfer between Sm^3＋ and Eu3＋ is investigated in detail.
The structure and photoluminescence （PL） properties of Sr3 SiO5： Sm3＋ and Li＋-doped Sr3SiOs： Sm3＋ red-emitting phosphors were investigated. Samples were prepared by the high-temperature solid-state method. PL spectra show that the concentration quenching occurs when the Sm3＋ concentration is beyond 1.3 mol% in Sr3SiOs： Sm3＋ phosphor without doping Li＋ ions. The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of Sm3＋ ions. The incorporation of Li＋ ions into Sr3SiOs： Sm3＋ phosphors, as a charge compensator, improves the PL properties. The lithium ions also suppress the concentration quenching in Sm3＋ with concentration increased from 1.3 tool% to 1.7 tool%.
A series of K3Gd（PO4）2：Tb3＋,Sm3＋ phosphors were synthesized through solid state reaction. By co-doping Tb3＋ and Sm3＋ into K3Gd（PO4）2 host and singly varying the doping concentration of Sm3＋, ttmable colors from green to yellow and then to orange were obtained in K3Gd（POa）2：Tb3＋,Sm3＋ phosphors under the excitation at 373 nm. The energy transfer process from Tb3~ to Sm3- was verified through luminescence spectra and fluorescence decay curves. Moreover, the energy transfer mechanism was demon- strated to be the quadrupole-quadrupole interaction. The results indicated that K3Gd（POa）2：Tb3＋,Sm3＋ phosphors could be a potential application for n-UV white light emitting diodes.
