Microwave Sol-Gel Preparation of NaLa(MoO4)2:Eu3+/Yb3+ Particles and Their Upconversion Photoluminescence Properties

Abstract

0.2 and Yb 3+ = 0.2, 0.45) were successfully synthesized by the microwave-modified sol-gel method, and the upconversion and spectroscopic properties were investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of 2-5 µm. Under excitation at 980 nm, NaLa0.5(MoO4)2:Eu0.05Yb0.45 particles exhibited a strong 525-nm emission band and a weak 550-nm emission band in the green region, and a very weak 665-nm emission band in the red region. The strong 525-nm emission in the green region corresponds to the 7 F1 → 5 D1 transition and the weak 550-nm emission in the green region corresponds to the 7 F0 → 5 D2 transition, while the very weak emission 665-nm band in the red region corresponds to the 5 D0 → 7 F3 transition. The Raman spectra of the doped particles indicated the domination of strong peaks at higher frequencies of 762, 890, 1358 and 1430 cm �1 and weak peaks at lower frequencies of 323, 388 and 450 cm �1 induced by the disorder of the [MoO4] 2� groups with the incorporation of the Eu 3+ and Yb 3+ elements into the crystal lattice or by a new phase formation.