Thermodynamic properties of complex oxides in the La-Ni-O system

摘要

Complex oxides La2NiO4+delta, LaN2O7-delta, La4Ni3O10-delta and LaNiO3-delta, the members of Ruddlesden-Popper series Lan+1NinO3n+1, were prepared using citrate precursors. The stability range of LaNiO3-delta in air as well as the oxygen nonstoichiometry of La3Ni2O7-delta and La4Ni3O10-delta as a function of temperature and oxygen partial pressure was determined by means of thermogravimetric technique. Decomposition temperatures of La3N2O7-delta, La4Ni3O10-delta and LaNiO3-delta in air were determined by conductivity measurement method. The boundary of stability for La4Ni3O10-delta was determined by EMF measurements of galvanic cell with oxygen conducting solid electrolyte. The isothermal (1400 K) projection of La-Ni-O system phase diagram to the plane "log(PO2)-relative mole fraction of metal components" was suggested. (c) 2006 Elsevier Inc. All rights reserved.