Elaboration and characterization of La2NiO4+δ powders and thin films via a modified sol-gel process

Polycrystalline thin films of La2NiO4 (+ delta) have been synthesized on yttria stabilized zirconia (YSZ) substrates by dip-coating using a polymeric sol. Crack-free films were obtained after sintering in air at temperatures ranging from 800degreesC to 1000degreesC. The microstructure, characterized by SEM, shows the formation of dense polycrystalline films with smooth surface and mean grains size of 140 nm, for films sintered at 1000degreesC. A correlation between grains size and non-stoichiometry in powders have been made in our processes. The thickness, evaluated for rugosimetry measurements, is thin (80 nm) and is a function of the viscosity of the sol. The higher the thickness, the higher the viscosity. As the non-stoichiometry level is controlled by the oxygen partial pressure, an evolution of non-stoichiometry in thin film has proposed. Then, it is possible by modifying synthesis and processing parameters to prepare thin films with a controlled microstructure (thickness, porosity and non-stoichiometry). (C) 2004 Elsevier Inc. All rights reserved.