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 Y₂O ₃, 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 Er ³⁺ ions.