X-ray analysis and optical studies of Dy3+ doped NaSrB5O9 microstructures for white light generation

Abstract

A white light emitting phosphor NaSrB5O9:Dy3+ 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 (P21/c). Williamson–Hall (W–H) analysis was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of NaSrB5O9:Dy3+ phosphors. Monoclinic microstructures of nearly plate-like morphologies were observed in the FE-SEM images. Upon near-UV excitation wavelength (390nm), the blue emission at ∼482nm (6H15/2) and yellow emission at ∼584nm (6H13/2) were observed in the phosphors. The critical quenching concentration of Dy3+ in NaSrB5O9 phosphor was found to be 3 at.% with the critical distance (Rc) of ∼22.30Å and the corresponding concentration quenching mechanism was testified to be the exchange interaction between the dopant Dy3+ 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 Dy3+ ions doped NaSrB5O9 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.