Synthesis of infrared up-conversion material SrS: Eu, Sm

Europium and samarium co-doped strontium sulfide (SrS: Eu, Sm) infrared up-conversion phosphor was synthesized through calcining the precursor, which was prepared by the wet method with strontium carbonate (SrCO3), sulfur (S), europium oxide (Eu2O3) and samarium oxide (Sm2O3) as the starting materials, and lithium fluoride (LiF), lithium carbonate (Li2CO3), natrium carbonate (Na2CO3) and potassium oxalate (K2C2O4) as the fluxing agents, at 750-1200°C in a carbon-reducing atmosphere. The effects of calcining temperature, calcining time, category and concentration of the fluxing agents and concentration of dopants on the final up-conversion luminescence properties were studied. The SrS crystal structure is formed primarily at 750°C, but the best calcining temperature should be 1100°C. The most suitable calcining time is 1-1.5 h, the up-conversion luminescence intensity increases along with the increase of time within this range and decreases above the range. Excellent up-conversion luminescence was obtained with 10% fluxing agent LiF and 0.2% dopants Eu and Sm. The up-conversion emission spectrum is a continuous broadband spectrum with one peak at 599 nm which resulted from the transitions of Eu2+5d(2T2g) → 4f(8S11/2).