Novel reddish-orange color emitting Ca2SiO4:Sm3+ phosphors for white LED applications prepared by using agricultural waste

Ca2SiO4:Sm3+ phosphors, where CaO and Si2O are synthesized from agricultural waste, are prepared through regular solid state reaction (SSR) technique. The XRD pattern confirmed their monoclinic structure and well matches with ICDD card No. 01-076-3612. The morphological studies through SEM images reveal that these were irregular in size and shape. Decay rates, emission and excitation spectra are measured to estimate the luminescent characteristics of Ca2SiO4:Sm3+ phosphors. The CIE chromaticity values are evaluated and it is shown in reddish-orange region. The luminescence is quenched for doping concentration of above 0.2 mol % of the Sm3+ ion owing to energy transfer through non-radiative process among the Sm3+ ions at different sites. The decay curves are exhibit near single exponential nature for lower (<= 0.1 mol %) Sm3+ ion concentrations and turns in to non-exponential nature for higher (>= 0.2 mol %) Sm3+ ion concentration. The lifetime values are increasing from 1.67 to 2.28 ms with decrease in concentration of Sm3+ ions from 0.3 to 0.01 mol %. These results suggest that the Ca2SiO4:Sm3+ phosphors were appropriate candidate for low cost white LED applications.