Crystal chemistry and photoluminescent investigation of novel white light emanating Dy3+ doped Ca9Bi(VO4)7 nanophosphor for ultraviolet based white LEDs

A novel series of white light emitting Ca9Bi(1−x)Dyx (VO4)7 nanophosphor has been prepared via urea-assisted solution combustion method for the very first time. Structural aspects of the synthesized nanophosphors are investigated by means of X-ray diffraction patterns. The Rietveld refinement performed on host Ca9Bi(VO4)7 and optimal luminescent composition Ca9Bi0.80Dy0.20(VO4)7 authenticate crystallization in trigonal lattice and space group as R3c (161). The emission spectra exhibit peaks due to 4F9/2 → 6H11/2, 13/2, 15/2 characteristic transitions of Dy3+ ions on excitation at 389 nm wavelength in ultraviolet region. The band gap for Ca9Bi(VO4)7 has been estimated to be 3.27 eV. The dipole-dipole type interactions are responsible for concentration quenching phenomena in trivalent dysprosium doped Ca9Bi(VO4)7 post 20 mol% composition of dopant ions. The intrinsic lifetime value (0.418 ms) and non-radiative rate (132.27 s−1) are determined by employing Auzel's model. The chromaticity coordinates (x = 0.288, y = 0.338), correlated color temperature (7760 K) and quantum efficiency value (95%) indicate towards a cool and efficient white light emanating Ca9Bi0.80Dy0.20(VO4)7 nanophosphor. The crystal and optical properties of the prepared nanophosphor vividly define its potential usage as ultraviolet triggered white light emitting source for lighting applications.