Investigation on the amounts of Na2CO3 and sulphur to obtain pure Y2O2S and up-conversion luminescence of Y2O2S:Er

The process to prepare pure phase of hexagonal Y2O2S was investigated. Effect of mixed flux of Na2CO3 and S amounts was studied. The phase composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the single phase of Y2O2S with smooth morphology could not be obtained as the molar ratio of Y2O3, Na2CO3 and S was in the range of 1:(0.5–1):(2–3) until the molar ratio was increased to 1:1.5:4. Different Er3+ concentration doped Y2O2S:Er powders were prepared with molar ratio of the raw materials 1:1.5:4. The quenching concentration of Er3+ in Y2O2S was more than 2 mol.%, which was due to the interaction of electric quadrupoles between Er3+ ions.