X-ray analysis and optical studies of Dy super(3+) doped NaSrB sub(5)O sub(9) microstructures for white light generation

A white light emitting phosphor NaSrB sub(5)O sub(9):Dy super(3+) was synthesized by a conventional solid state reaction method. The structure of the phosphors was analyzed by powder X-ray diffraction (XRD), revealing that the phosphors crystallized in monoclinic crystal structure with the space group (P2 sub(1)/c). Williamson-Hall (W-H) analysis was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of NaSrB sub(5)O sub(9):Dy super(3+) phosphors. Monoclinic microstructures of nearly plate-like morphologies were observed in the FE-SEM images. Upon near-UV excitation wavelength (390 nm), the blue emission at ~482 nm ( super(6)H sub(15/2)) and yellow emission at ~584 nm ( super(6)H sub(13/2)) were observed in the phosphors. The critical quenching concentration of Dy super(3+) in NaSrB sub(5)O sub(9) phosphor was found to be 3 at.% with the critical distance (R sub(c)) of ~22.30 A and the corresponding concentration quenching mechanism was testified to be the exchange interaction between the dopant Dy super(3+) ions. In order to investigate the application in white LEDs, the Commission International de l'Eclairage (CIE) chromaticity coordinates, color temperature and decay curve measurements of Dy super(3+) ions doped NaSrB sub(5)O sub(9) phosphors were carried out. The yellow to blue (Y/B) emission integrated intensity ratio is maximum (~0.9) for all the concentrations, suggesting that the phosphors favor for white illumination.