Spectral investigations on Eu 3+ ,Sm 3+ ‐doped and Sm 3+ /Eu 3+ co‐doped potassium‐fluoro‐phosphate glass emitting intense orange‐red for lighting applications

Potassium fluoro‐phosphate (KFP) glass singly doped with different concentrations of europium (Eu 3+ ) or samarium (Sm 3+ ) or co‐doped (Sm 3+ /Eu 3+ ) was prepared, and their luminescence spectra were investigated. The phase composition of the product was verified by X‐ray diffraction analysis. Optical transition properties of Eu 3+ in the studied potassium phosphate glass were evaluated in the framework of the Judd–Ofelt theory. The radiative transition rates (A R ), fluorescence branching ratios (β), stimulated emission cross‐sections (σ e ) and lifetimes (τ exp ) for certain transitions or levels were evaluated. Red emission of Eu 3+ was exhibited mainly by the 5 D 0 → 7 F 2 transition located at 612 nm. Concentration quenching and energy transfer were observed from fluorescence spectra and decay curves, respectively. It was found that the lifetimes of the 5 D 0 level increased with increase in concentration and then decreased. By co‐doping with Sm 3+ , energy transfer from Sm 3+ to Eu 3+ occurred and contributed to the enhancement in emission intensity. Intense orange‐red light emission was obtained upon sensitizing with Sm 3+ in KFP glass. This approach shows significant promise for use in reddish‐orange lighting applications. The optimized properties of the Sm 3+ /Eu 3+ co‐doped potassium phosphate glass might be promising for optical materials.