Abstract

• Lanthanum based pervoskite type oxides are attractive materials due to their interesting optical, electric and magnetic properties as well as their potential applications. LaCo1-xFexO3(0.1 ≤ X ≤ 0.4) nanocrystalline powders were prepared by the use of lanthanum nitrate, cobalt nitrate, ferric nitrate as starting materials, citric acid as chelating agent and ethylene glycol as a gelification agent by citrate sol-gel method. The prepared samples were designated as LCFO-SG-I for LaCo0.6Fe0.4O3, LCFO-SG-II for LaCo0.7Fe0.3O3, LCFO-SG-III for LaCo0.8Fe0.2O3 and LCFO-SG-IV for LaCo0.9Fe0.1O3. The prepared LaCo1-xFexO3(0.1 ≤ X ≤ 0.4) nanocrystalline powders were characterized by modern techniques (Thermogravimetry/Differential Thermal Analysis, X-ray Diffractometry, Fourier Transform Infrared Spectroscopy, Energy Dispersive X-ray Fluorescence and Scanning Electron Microscope). The effect of calcination temperatures was investigated on LaCo0.6Fe0.4O3. From the XRD analysis, the single phase perovskite structure was obtained after the sample were calcined at 500 .C. It was found that LaCo1-xFexO3 (0.1 ≤ X ≤ 0.4) nanocrystalline powders were single pervoskite phase, good crystallinity and average crystallite sizes at 600 .C calcination temperature. From the TG-DTA thermogram of the prepared powders calcined at 600 .C, the weight loss percents of all prepared samples are very low and therefore they have thermal stability. Relative abundances of elements analyzed by EDXRF showed lanthanum, cobalt and iron as the major constituents in the prepared powders. From FT IR spectral data, as the organic groups were removed during calcination, the band observed between 1470 and 1390 cm-1 is due to C-H stretching of residual carbon. Only the stretching vibration of metal-oxygen bond in the frequency range between 599 and 406 cm-1were observed. From the SEM micrographs, the LaCo1-xFexO3(0.1 ≤ X ≤ 0.4) nanocrystalline powders have highly porous nature and agglomerates depending on the calcination temperatures and Fe doping levels.