Concentration dependent spectroscopic behavior of Sm3+ doped leadfluoro-borophosphate glasses for laser and LED applications

A new series of Sm3+ doped leadfluoro-borophosphate glasses with the composition 50B(2)O(3)+(20-x) P2O5+10Li(2)O+10ZnF(2)+10PbO + xSm(2)O(3) (where x = 0, 0.05, 0.1, 0.25, 0.5, 1 and 2 in wt%) were prepared by following the melt quenching technique and their structural and spectroscopic behavior were studied through XRD, FTIR, optical absorption, luminescence and decay measurements. The presence of fundamental vibrational groups such as BO3, BO4 and PO4 were explored through the FTIR spectral measurements and further increasing BO4 units with NBO were also found out. The nephelauxetic effect and Judd-Ofelt (JO) theory have been applied to investigate the nature of the Sm-O bond and the local environment around the Sm3+ ion site. The luminescence intensity decreases with the increase in Sm3+ ion concentration beyond 0.5 wt% and the same was discussed through various energy transfer mechanism which takes place between Sm3+ ions. The lasing parameters like stimulated emission cross-section (sigma(E)(P)), branching ratios (beta(R)) and radiative lifetime (tau(cal)) for the (4)G(5/2) -> H-6(5/2), (4)G(5/2) -> H-6(7/2), (4)G(5/2) -> H-6(9/2) and (4)G(5/2) -> H-6(11/2) emission transitions have been calculated, discussed and reported. The R/O intensity ratios have been studied by varying the RE ion concentration and further CIE color chromaticity coordinates have also been calculated to characterize the emission of the prepared glasses. The color purity and the correlated color temperature were also calculated and the results were discussed in the present work. The decay of the (4)G(5/2) excited level is found to be single exponential upto 0.1 wt% and after that it changes into non-exponential for higher concentration and the non-exponential behavior arises due to the energy transfer between the Sm3+ ions through various cross-relaxation channels and the decay of the (4)G(5/2) excited level have been analyzed with IH model. Among the prepared glasses, BPLP0.5S glass exhibits higher sigma(E)(p), beta(R), sigma(E)(p) x tau(R) and sigma(E)(p) x Delta lambda(eff) values corresponding to the (4)G(5/2) -> H-6(7/2) emission band and these are in turn specifies its suitability for LEDs and visible laser applications. (C) 2015 Elsevier B.V. All rights reserved.