The study of structural and optical properties of (Eu, La, Sm) codoped ZnO nanoparticles via a chemical route

Abstract The (Eu, La, Sm) ions were doped into ZnO nanoparticles by a chemical route, and the substitution of (Eu, La, Sm) for Zn 2+ ions was proved by analytic techniques of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, transmission electron microscope (TEM), photoluminescence (PL) and UV–vis absorption spectroscopy. The results revealed that the codoping did not change the wurtzite structure of ZnO nanoparticles, but the diameter of the nanoparticles decreased with increasing the rare earth (RE) doping concentrations. The optical bandgaps calculated through UV–visible absorption spectroscopy were found to decrease from 3.26 to 3.14 eV with increasing the RE doping concentrations, which also proved by the slight shift of UV positions in PL spectra. The sharp red emissions located at 578.2, 590.1 and 615.7 nm were originated from the 4f-4f transitions in Eu 3+ ions under excitation of 325 nm. And these red emissions of Eu 3+ ions showed a strong correlation with the energy storage centers of oxygen vacancies in the samples which was introduced by the other RE ions of La 3+ and Sm 3+ codoping.