Preparation of perovskite-type oxide, LaFeO3, by low-temperature decomposition of heteronuclear coordination polymer, (NH4)La[Fe(CN) 6] · 4.5H2O

Abstract

Thermal decomposition of the coordination polymer, (NH4) La[FeII(CN)6] · 4.5H2O, with a three-dimensional network structure formed by the FeIICNLa III linkages, was investigated. The decomposition began at around 323K and proceeded via a few steps to give the anhydride complex, (NH 4)La[FeII(CN)6], at around 523K. Further heating gave rise to an abrupt collapse of cyanide groups at around 573 K, followed by the initial formation of the perovskite-type oxide, LaFeO 3, at 603K and the completion of the decomposition to produce LaFeO3 at around 898K. Any formation of the component metal oxides, La2O3 and Fe2O3, was not recognized during the decomposition. From the XRD line broadening using Scherrer's equation, the average size of the thermal decomposition product was evaluated to be 21, 22, 25 and 30nm at 773, 823, 898 and 1073 K, respectively. The specific surface area of the LaFeO3 particles prepared at 898, 1073 and 1273K was 13.2, 8.6 and 2.5m2 g-1, respectively. © 2010 The Ceramic Society of Japan. All rights reserved.