Effect of starting materials on the morphological and optical properties of Er doped BaTiO₃ nanocrystalline films

Erbium (5%mol) doped BaTiO₃ films were prepared using different metallic precursors: barium acetate, titanium butoxide and isopropoxide with different molar ratios. Three different experimental methodologies (A, B and C) were proposed in order to obtain optical quality thick films incorporating polyvinylpyrrolidone (PVP) as a rheological agent at the sol stage. In all cases, Er doped BaTiO₃ films were deposited in silica quartz substrates. The morphology was controlled by means of the incorporation of the chelating agent and water molar ratios. Through the three different synthesis routes, Er:BaTiO₃ films presented mainly the cubic phase, as observed by X-ray diffraction. The films presented a homogeneous and crack-free surface of cross-linked particles. Photoluminescent results show that the highest intensity emission of the Er³⁺ (⁴S_3/2→ ⁴I_15/2) was obtained from Er:BaTiO₃ film prepared using C methodology, which could be associated with the film's thicknesses.