Novel high color purity and thermally stable Eu3+ ions activated Ba2Gd5B5O17 red emitting phosphor for near-UV based WLEDs

Abstract

Novel Eu3+ doped Ba2Gd5B5O17 phosphors were synthesized by solid-state reaction technique. The phase identification and photoluminescence properties were investigated through XRD, FE-SEM, photoluminescence (PL), decay curves and temperature dependent PL spectral measurements. The XRD studies confirm the formation of single phase Ba2Gd5B5O17 phosphors and the addition of Eu3+ ions does not modify host lattice crystal structure. From FE-SEM analysis, it is noticed that prepared phosphors are comprise of micro-particles with an average particle size about 5.2 μm. Under the excitation of 396 nm, as-prepared Ba2Gd5-xEuxB5O17 phosphors exhibited intense red emission and their PL intensity was increased with the increase of Eu3+ content up to x = 0.5, beyond that it was decreased for higher Eu3+ ion concentration due to concentration quenching effect. In the present work, non-radiative energy transfer was responsible for concentration quenching and the critical distance of energy transfer was found to be 11.3 Å. Further, the PL spectra were characterized through CIE 1931 diagram to explore the dominant emission color. Furthermore, the R/O ratio, color purity, internal quantum efficiency and activation energy for thermal quenching effect were calculated for studied Ba2Gd4.5Eu0.5B5O17 phosphor. The obtained results were compared with the previously reported literature and discussed in detail.