Synthesis, photoluminescence, Judd-Ofelt analysis, and thermal stability studies of Dy3+-doped BaLa2ZnO5 phosphors for solid-state lighting applications.

Abstract

Here, we report a series of white-emitting Ba(La2-x Dy x )ZnO5 (x = 0-7 mol%) phosphors synthesized via a high-temperature solid-state reaction. The synthesized phosphor's phase purity and tetragonal crystal structure were confirmed by an X-ray powder diffraction (XRPD) pattern. The wide bandgap characteristic feature was assessed through reflectance spectra, and the estimated bandgap was found to be 4.70 eV. Besides analyzing the effect of doping on the surface morphology, the distribution of ions on the surface was observed through the secondary ion mass spectroscopy technique. The synthesized phosphor was found to display bluish (486 nm) and yellowish (576 nm) bands in the emission spectra under the excitation of 325 nm and 352 nm, which together are responsible for producing the white luminescence. The analysis of Judd-Ofelt parameters indicates the symmetric nature of Dy3+ substitution in the present host. The thermal stability of the phosphor was assessed by varying the temperature up to 403 K, and it was found that the synthesized phosphor possesses improved thermal stability with an activation energy of 0.29 eV. The photometric evaluations of the present phosphor revealed the CIE coordinates around the near-white regime (0.3448, 0.3836), along with the color-correlated temperature value of 5102 K. All research on this luminescent material's unique features points to the possibility of using it to fabricate white-light-emitting devices for solid-state lighting applications.