Spectral investigations on Eu3+,Sm3+‐doped and Sm3+/Eu3+ 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 (Eu3+) or samarium (Sm3+) or co‐doped (Sm3+/Eu3+) 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 Eu3+ in the studied potassium phosphate glass were evaluated in the framework of the Judd–Ofelt theory. The radiative transition rates (AR), fluorescence branching ratios (β), stimulated emission cross‐sections (σe) and lifetimes (τexp) for certain transitions or levels were evaluated. Red emission of Eu3+ was exhibited mainly by the 5D0→7F2 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 5D0 level increased with increase in concentration and then decreased. By co‐doping with Sm3+, energy transfer from Sm3+ to Eu3+ occurred and contributed to the enhancement in emission intensity. Intense orange‐red light emission was obtained upon sensitizing with Sm3+ in KFP glass. This approach shows significant promise for use in reddish‐orange lighting applications. The optimized properties of the Sm3+/Eu3+ co‐doped potassium phosphate glass might be promising for optical materials.