Structural and electrical properties of calcium substituted lanthanum ferrite powders

Abstract

Pure and calcium substituted lanthanum ferrite compounds, La 1 − x Ca x FeO 3 − δ (x = 0, 0.05, 0.1 and 0.2), were successfully synthesized using the polymerizable complex method. Several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and complex impedance analysis (CIA) were used to characterize the obtained samples. Whatever the calcium concentration, all the compounds are identified as single perovskite phases. No significant morphological changes are noted upon lanthanum substitution. All the prepared powders are composed of fine and homogeneous particles with a crystallite size ranging from 32 nm (for LaFeO 3 ) to 12 nm (for La 0.8 Ca 0.2 FeO 3 − δ ). A noticeable improvement of electrical conductivity is noted with increasing calcium amounts. In particular, it was found that La 0.8 Ca 0.2 FeO 3 − δ conductivity is thirty times higher than that of the parent lanthanum ferrite oxide. The preparation of pure and calcium substituted lanthanum ferrite powders was investigated. All the prepared compositions were single perovskite phases with orthorhombic structure. The powders are composed of fine particles with homogeneous grain size distribution. ► Lanthanum ferrite powders are synthesized at 900 °C. ► Single perovskite phases are obtained. ► Homogeneous microstructures are observed by SEM. ► High substitution level results in an improvement of electric conduction.