Dy3+ doped calcium boroaluminate glasses and Blue Led for smart white light generation

Dy2O3 doped calcium boroaluminate (CaBAl) glasses (50) B2O3-(25-x) CaO-(15) Al2O3-(10) CaF2-(xDy(2)O(3)) (x = 0.0, 0.5, 1, 2, 3, and 5 wt%) were prepared by using the conventional melt-quenching technique and characterized through XRD, FTIR, refractive index, volumetric density, absorption, excitation, photoluminescence and lifetime measurements. The amorphous nature of the CaBAl glasses was confirmed through XRD measurements. FTIR analysis allowed identifying stretching and bending vibrations of different borate groups. Absorption spectra presented characteristic peaks of Dy3+, corresponding to transitions from the H-6(15/2) ground state to the excited energy levels. Oscillator strengths and Judd-Ofelt intensity parameters (ohm(t) = 2, 4 and 6) were calculated from the absorption spectra. The photoluminescence spectra of the Dy3+ doped CaBAl glasses, under 405 nm excitation, exhibited two intense emission bands corresponding to the F-4(9/2) -> H-6( )15/2 (blue) and F-4(9/2) -> H-6(13/2) (yellow) transitions. The intensity of Dy3+ emission spectra increased with Dy2O3 content from 0.5 wt% to 3 wt% and concentration quenching was observed for concentrations higher than 3 wt %. The yellow/blue (Y/B) ratio was investigated as a function of Dy2O3 content. The simulation of a combination of a Blue LED (BL) emission with the sample emission was also studied in the CIE diagram, in order to evaluate the possibility of smart white light generation. Photoluminescence decay curves, fitted by Inokuti-Hirayama model (S = 6), indicates a dipole-dipole interaction between donor and acceptor Dy3+ ions in the glass. All results suggest that the investigated CaBAl:Dy3+ glasses are candidates for W-LEDs application and smart lighting.