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The commercially available white-light-emitting diodes (WLEDs) are made with a combination of blue LEDs and yellow phosphors. These types of WLEDs lack certain properties which make them meagerly applicable for general illumination and flat panel displays. The solution for such problem is to use near-ultraviolet (NUV) chips as an excitation source because of their high excitation efficiency and good spectral distribution. Therefore, there is an active search for new phosphor materials which can be effectively excited within the NUV wavelength range (350–420 nm). In this work, novel rare-earth free self-luminescent Ca2KZn2(VO4)3 phosphors were synthesized by a citrate assisted sol-gel method at low calcination temperatures. Optical properties, internal quantum efficiency and thermal stability as well as morphology and crystal structure of Ca2KZn2(VO4)3 phosphors for their application to NUV-based WLEDs were studied. The crystal structure and phase formation were confirmed with XRD patterns and Rietveld refinement. The optical properties of these phosphor materials which can change the NUV excitation into visible yellow-green emissions were studied. The synthesized phosphors were then coated onto the surface of a NUV chip along with a blue phosphor (LiCaPO4:Eu2+) to get brighter WLEDs with a color rendering index of 94.8 and a correlated color temperature of 8549 K.

Spherical yttrium gallium garnet (Y 3 Ga 5 O 12) samples were prepared by a single-step hydrothermal synthesis method, and these particles were coated with silver oxide (Ag 2 O) nanoparticles by following a facile wet chemical approach at ambient temperature. The structural, morphological, vibrational and optical properties of the as-prepared and Ag 2 O modified Y 3 Ga 5 O 12 samples were analyzed. From Rietveld refinement of X-ray diffraction patterns, the crystal structure of the Y 3 Ga 5 O 12 sample was refined. The morphological properties confirmed that the particles were spherical and their surfaces were covered with Ag 2 O nanoparticles. The Ag 2 O modified Y 3 Ga 5 O 12 sample exhibited a relatively enhanced photocatalytic activity compared to the pure Y 3 Ga 5 O 12 sample in Rhodamine B solution, suggesting that the introduction of Ag 2 O broadens the absorption of light and controls the photogenerated carrier recombination in Y 3 Ga 5 O 12. These results provide a clear perspective on the synthesis of hybrid photocatalyst materials which have several ways of photogenerated carrier migration. Recently, Jiang et al. have reported Y 3 Al 5 O 12 :Ce 3+ (YAG: Ce 3+) semiconductor particles mixed with TiO 2 as an effective photocatalytic material. 16 Similarly, Feng et al. also described the effect of YAG:Er 3+ on the photocatalytic activity of TiO 2 nanocrystals. 17 The TiO 2 particles showed enhanced photocatalysis with the addition of the semiconductor particles. More recently, Wang et al. have reported the influence of Gadoped Er 3+ :YAG on the solar light photocatalytic activity of

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