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

Abstract

A novel series of white light emitting Ca 9 Bi (1− x ) Dy x (VO 4 ) 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 Ca 9 Bi(VO 4 ) 7 and optimal luminescent composition Ca 9 Bi 0.80 Dy 0.20 (VO 4 ) 7 authenticate crystallization in trigonal lattice and space group as R 3 c (161). The emission spectra exhibit peaks due to 4 F 9/2 → 6 H 11/2, 13/2, 15/2 characteristic transitions of Dy 3+ ions on excitation at 389 nm wavelength in ultraviolet region. The band gap for Ca 9 Bi(VO 4 ) 7 has been estimated to be 3.27 eV. The dipole-dipole type interactions are responsible for concentration quenching phenomena in trivalent dysprosium doped Ca 9 Bi(VO 4 ) 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 Ca 9 Bi 0.80 Dy 0.20 (VO 4 ) 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.