Synthesis of SrWO4:[Er3+]/[Yb3+] Upconversion Phosphor

Barium acetate ((CH₃CO₂)₂Sr, Sigma-Aldrich), sodium tungstate (Na₂WO₄·2H₂O, Sigma-Aldrich), ytterbium(iii) nitrate pentahydrate (Yb(NO₃)₃·5H₂O, Yb³⁺), and erbium(iii) nitrate pentahydrate (Er(NO₃)₃·5H₂O, Er³⁺). 10 mmol of (CH₃CO₂)₂Sr was dissolved in beaker “A” containing 100 ml of distilled water. In beaker “B”, 10 mmol of Na₂WO₄·2H₂O was dissolved in 100 ml distilled water (Fig. 1). The solution that was completely dissolved in beaker “B” was slowly poured into a stirring beaker “A” and remained there for about 20 minutes. After that, powder was recovered using a centrifuge (4000 rpm, 5 min), and the powder was prepared by rinsing with distilled water 3 times to remove any remaining sodium. The powder was dried in an oven at 80 °C for 16 hours. The up-conversion phosphor was synthesized with SrWO₄ as a host, the precursor made by simultaneously adding Yb(NO₃)₃·5H₂O and Er(NO₃)₃·5H₂O to beaker “A”. The prepared precursor was sintered at 800 °C until the SrWO₄:[Er³⁺]/[ Yb³⁺] phosphor was synthesized. Rare earth [RE] ions of Yb³⁺ were fixed at 0.5 mmol, and the amount of Er³⁺ (0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5 mmol) added changed ([Er³⁺]/[Yb³⁺] ∼ 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1).^{20,21 (link)}