White light-emitting diode (WLED) products currently available on the market are based on the blue LED combined with yellow phosphor approach. However, these WLEDs are still insufficient for general illumination and flat panel display (FPD) applications because of their low color-rendering index (CRI < 75) and high correlated color temperature (CCT = 6000 K). Although near-ultraviolet (UV) LED chips provide more efficient excitation than blue chips, YAG:Ce3+ phosphors have very weak excitation in the near-UV spectral region. Hence, there is an increasing demand for novel yellow phosphor materials with excitation in the near-UV region. In this work, we report novel self-activated yellow Ca5Zn3.92In0.08(V0.99Ta0.01O4)6 (CZIVT) phosphors that efficiently convert near-UV excitation light into yellow luminescence. The crystal structure and lattice parameters of these CZIVT phosphors are elucidated through Rietveld refinement. Through doping with In3+ and Ta5+ ions, the emission intensity is enhanced in the red region, and the Stokes shift is controlled to obtain good color rendition. When a near-UV LED chip is coated with a combination of CZIVT and commercial blue Ba0.9Eu0.1MgAl10O17 phosphors, a pleasant WLED with a high CRI of 82.51 and a low CCT of 5231 K, which are essential for indoor illumination and FPDs, is achieved.

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Oxyapatite Ca2Gd8(SiO4)6O2 (CGS) nanostructures with nanorod bundle-like morphology are prepared by mixed solvothermal and hydrothermal reaction methods. Detailed structural and morphological studies are performed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy measurements. CGS nanorod bundles are formed by crystal splitting, and the growth mechanism as a function of reaction time is discussed. The size and crystal splitting of the nanorod bundles are controlled by varying the concentration of 2-propanol. The annealing temperature does not have any effect on the morphology of CGS nanorod bundles, and the bundles can sustain high temperatures, which confirms the crystal splitting of nanorod bundles. Photoluminescence and cathodoluminescent studies are carried out by activating the Eu3+ ions in the CGS host lattice as a function of annealing temperature. The corresponding CIE chromaticity coordinates are in close proximity to the commercial red emitting phosphor chromaticity coordinates.