Non-stoichiometric La(1x)NiO(3-delta) perovskites produced by combustion synthesis

La(1-x)NiO(3-delta) perovskites present high metallic conductivity and Paul i-paramagnetism, and could be used as electrodes in electrochemical devices such as SOFCs, PEMFCs and MCFCs. Additionally, due to its sigma* conductin g band, this material shows a very high electrocatalytic activity, particul arly in oxygen reduction processes, with an efficiency comparable to that o f platinum. This work describes the combustion synthesis of La(1-x)NiO(3-de lta) perovskite powders (x=0 and 0.1) from mixtures of La(NO3)(3). 6H(2)O a nd Ni(NO3)(2). 6H(2)O as cation precursors, and urea as fuel. The as-prepar ed combustion product, characterized by XRD, DTA/TG, SEM/TEM, BET and dilat ometry (after compaction), shows a much higher specific surface area than p owders obtained via alternative routes and contains La2NiO4 with a typical K2NiF4-type structure, together with small amounts of NiO. The usual subseq uent heat treatments for 1 to 12 h at successively higher temperatures show ed that full conversion to La(1-x)NiO(3-delta) can be readily achieved in a ir at 750 degrees C and that the perovskite, after the 12 h heat treatment, remains stable up to 1100 degrees C. These results show that the combustio n technique is a better and much simpler route to the synthesis of perovski te powders.