Oxygen vacancy ordering in superlatives of the two novel oxides, La2Ni2O5 and La2Co2O5, prepared by low temperature reduction of the parent perovskites

Controlled reduction of LaBO3(B = Co or Ni) perovskites gives rise to ordered structures of composition La2B2O5, belonging to the homologous series LanBnO3n–1, which retain the original features of the perovskite; the co-ordination of the transition metal ions differ, with Ni2+ ions showing octahedral and square-planar co-ordination and the Co2+ ions showing octahedral and tetrahedral co-ordination.