Near-infrared upconversion in ZnO/RE2O3 (RE = Nd, Yb) composites prepared by thermal decomposition
摘要
In this study, ZnO/RE2O3 (RE = Nd, Yb) composites were prepared using the thermal decomposition method. The neodymium concentration was fixed at 2 mol%, while the ytterbium content was varied (0, 3, and 6 mol%) to investigate its influence on the morphological, structural, and optical properties of the material. X-ray diffraction confirmed the formation of the hexagonal wurtzite phase of ZnO, along with secondary phases of rare-earth oxides. Scanning electron microscopy revealed the formation of micro- and nanoparticles in the as-synthesized powders, with a transition into larger sintered structures after annealing. Photoluminescence studies showed the characteristic green-yellow emission of ZnO around 550 nm, which was partially quenched by Yb3+. Under 975 nm excitation, upconversion luminescence was observed with bands at 755 nm, 809 nm, and 871 nm, attributed to Nd3+ transitions sensitized by Yb3+ ions through phonon-assisted energy transfer mechanism. The excitation power dependence revealed a two-photon mechanism for the 755 nm and 809 nm bands, and a one-photon process for the 871 nm emission. The highest upconversion intensity was obtained for the sample containing 2 mol% Nd3+ and 6 mol% Yb3+. This work provides new insights into the underlying energy transfer mechanisms and demonstrates that compositional control is an effective strategy to optimize near-infrared upconversion performance in high-phonon-energy materials, highlighting their potential for advanced photonic applications.