p(O2)-stability of LaFe1-xNixO3-δ solid solutions at 1100 °C

LaFe1-xNixO3-delta (X=0.1-1.0) perovskites were synthesized via citrate route. The p(O-2)-stability of the perovskite phases LaFe1-xNixO3-delta has been evaluated at 1100 degrees C based on the results of XRD analysis of powder samples annealed at various p(O-2) and quenched to room temperature. The isothermal LaFeO3-delta-LaNiO3-delta cross-section of the phase diagram of the La-Fe-Ni-O system has been proposed in the range of oxygen partial pressure -15 < log p(O-2)/atm <= 0.68. The unit cell parameters of orthorhombic perovskites O-LaFe1-xNixO3-delta increase with decrease in p(O-2) at fixed composition x. This behavior is explained on the basis of size factor. The decomposition temperatures of rhombohedral phases R-LaFe1-xNixO3-delta for x=0.7, 0.8, 0.9 and 1.0 in air were determined as 1137, 1086, 1060 and 995 degrees C, respectively. (C) 201 0 Elsevier Inc. All rights reserved.