Preparation of PbLa2(MoO4)4:Er3+/Yb3+ particles via microwave sol–gel route and upconversion photoluminescence properties

Abstract

PbLa2−x(MoO4)4:Er3+/Yb3+ phosphors with doping concentrations of Er3+ and Yb3+ (x=Er3++Yb3+, Er3+=0.05, 0.1, 0.2 and Yb3+=0.2, 0.45) were successfully synthesized via microwave sol–gel route, and upconversion photoluminescence properties were investigated. Well-crystallized particles, formed after heat-treatment at 900°C for 16h, showed a fine and homogeneous morphology with particle sizes of 2–5μm. Under excitation at 980nm, PbLa1.7(MoO4)4:Er0.1Yb0.2 and PbLa1.5(MoO4)4:Er0.05Yb0.45 particles exhibited a strong 525nm emission band, a medium 550nm emission band in the green region, and a very weak 655nm emission band in the red region. The Raman spectra of the doped particles indicated the presence of strong peaks at higher and lower frequencies induced by disordered structures of PbLa2−x(MoO4)4 by the incorporation of the Er3+ and Yb3+ ions into the crystal lattice, which resulted in the unit cell shrinkage accompanying the highly modulated structure with anion deficient MoO4−x group.