Abstract:Erbium-doped BaTiO₃ films on LaNiO₃/Si substrates were fabricated by sol−gel method. The crystalline structure, morphologies and upconversion (UC) luminescence properties of films were respectively investigated by X-ray diffraction (XRD), atomic force microcopy (AFM) and photoluminescence (PL). The results indicate that both of the microstructure and luminescence are found to be dependent on Er³⁺ substituting sites. The samples with A-site substitution have smaller lattice constants, larger grains and smoother surface than those with B-site substitution. The photoluminescence spectra show that both of the samples have two stronger green emission bands centered at 528 and 548 nm and a weak red emission band centered at 673 nm, which correspond to the relaxation of Er³⁺ from ²H_11/2, ⁴S_3/2, and ⁴F_9/2 levels to the ground level ⁴I_15/2, respectively. Compared with B-site doped films, A-site doped films have a stronger integrated intensity of green emissions and a weaker relative intensity of red emissions. The differences could be explained by the crystalline quality and cross relaxation (CR) process.

Key words: Er³⁺ doping; BaTiO₃ thin films; upconversion photoluminescence; sol−gel method