Structural, morphological, spectral properties and high quantum efficiency of Eu3+, B3+ co-activated double perovskite Ba2GdMO6 (M = Nb, Ta) phosphors

Abstract

The influence of boron on the structural, morphological, and spectral properties was examined using Ba2Gd1−xMO6 (M = Nb, Ta) double perovskite ceramics co-doped with xEu3+ and yB3+ (x = 10 mol%, y = 0, 5, 15, 30, 50, 70, 100 mol%), which were synthesized through the solid-state method. X-ray diffractions of all the samples revealed a single-phase structure, and SEM micrographs of B3+, Eu3+ doped grains showed that the flux effect of boron promotes grain growth. The optical band gap energy was calculated from UV–Vis reflectance spectra, where Eg values decreased between 0 and 100 B3+. PL emissions of phosphors increase up to 50 mol% B3+ concentration due to increasing grain size and improving crystallinity, while a somewhat increase occurred in the asymmetry ratio for both series. The increase of the Judd-Ofelt (JO) parameters (Ω2 and Ω4) with increasing B3+ was associated with the decreasing local symmetry of Eu3+ sites and the decreasing electron density in the ligands. Moreover, while the increase of boron improved the quantum efficiency of phosphors, the ηQE% values of 50 mol% B3+ concentration were 80.84 % and 98.02 % for Ba2Gd1-xMO6:xEu3+, yB3+ (M = Nb, Ta), respectively. The paper may provide an alternative perspective and a new strategy for the structural, morphology, and luminescence efficiency of RE3+-doped double perovskite phosphors.