Spectral studies of Eu3+ doped lithium lead alumino borate glasses for visible photonic applications

Abstract

Quaternary lithium lead alumino borate (LiPbAlB) glasses doped with different concentration of Eu3+ ions have been synthesized by melt quench technique and characterized by using XRD, Photoluminescence (PL), PL decay and CIE-chromaticity co-ordinates to understand their luminescence behavior. A broad hump observed in the XRD spectrum confirms glassy nature of the as-prepared un-doped glasses. By applying Judd-Ofelt (J-O) theory to the emission spectra, various radiative parameters for the prominent fluorescent levels of Eu3+ have been evaluated. An intense excitation peak observed at 393 nm matches well with the excitation wavelength of n-UV LED chip. The PL intensity increases up to 7 mol% of Eu3+ in LiPbAlB glasses and beyond quenching observed. The decay profiles observed for the prominent emission line 5D0 → 7F2 were well fitted to bi-exponential function and lifetime are decreasing with increase in Eu3+ ion concentration which may be due to efficient energy transfer between Eu3+-Eu3+ through cross relaxation channels. CIE chromaticity co-ordinates evaluated from the emission spectra, are found to be in red region of the visible spectrum. The enhanced color purity and quantum efficiency values were also evaluated from the emission spectral data. From the emission cross-sections, branching ratios, quantum efficiency, CIE coordinates and color purity, it was concluded that 7 mol% of Eu3+ ion concentration (glass C) is optimum in LiPbAlB glasses for visible red photonic device application.