Optimization of processing parameters for preparation of LaNiO3 thin films from the citrate precursors

LaNiO3 precursor solution was prepared by a modified Pechini method, using citric acid, lanthanum oxide and nickel acetate. Phase evolution in the dried solution was studied by DTA. Crystallisation was completed by 790 C. Pt substrates were spin coated with the precursor solution, and different thicknesses annealed at 600-800 C, to establish the optimum solution concentration, annealing temperature and number of layers. The microstructure of the resulting thin films was studied by atomic force microscopy and SEM, and the phase composition determined by XRD. Films prepared using a solution concentration of 0.2 M exhibited large cracks, whilst those prepared at a concentration of 0.1 M were amorphous at 600 C, and well-crystallised, dense and crack-free when annealed at 700 C. These films were amorphous following heat treatment at 800 C, attributed to degradation of the LaNiO structure. 18 refs.