Fabrication of Microcrystalline NaPbLa(WO4)3:Yb Yb3+/Ho3+ Phosphors and Their Upconversion Photoluminescent Characteristics

Abstract

New triple tungstate phosphors NaPbLa(WO4)3:Yb Yb3+/Ho3+ x = Yb 3+3+/Ho 3+ = 7, 8, 9, 10 ) were successfully fabricated by microwave assisted sol gel synthesis and their structural and frequency upconversion (UC) characteristics were investigated. The compounds crystallized in the tenragonal space group I 4 1 a and the NaPbLa(WO 4 3 host has unit cell parameters a = 5.3927(1) and c = 11.7961(3) Å, V = 343.05(2) Å 3 , Z = 4. Under the excitation at 980 nm , the phosphors have yellowish green emissions , which were derived from the intense 5 S 2 5 F 4 → 5 I 8 transitions of Ho 3+ ions i n the green spectral range and the strong 5 F 5 → 5 I 8 transitions in the red spectral range The optimal Yb3+:Ho3+ ratio was revealed to be x = 9, which was attributed to the quenching effect of Ho3+ ions, as indicated by the composition dependence. The UC characteristics were evaluated in detail under onsideration of the pump power dependence and Commission Internationale de L'Eclairage chromaticity. The spectroscopic features of Raman spectra were discussed in terms of superposi ti on of Ho 3+ luminescence and vibrational line s.