Structural and Spectroscopic Studies of Nanostructured Alumina Doped LaFeO₃ a Photo catalyst Ceramics Synthesized Through an Auto Igniting Combustion Synthesis

LaFeO₃ with an orthorhombic phase of the ABO₃ type perovskite structure has become a currently attractive research topic because it is proposed for various applications in several advanced technologies such as catalysts, various kinds of chemical and gas sensors and electrode materials in solid oxide fuel cells. In the present work La_1-xAl_xFeO₃ (x = 0.01) nanopowder was prepared through an auto ignited combustion technique. In order to study the phase stability, the structural, vibrational and optical properties, the as prepared material was heat treated at 600°C. The phase purity of the powder was examined using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies. XRD studies show that the powder possesses an orthorhombic structure with lattice constants a=5.55, b=7.85 and c=5.55. The transmission electron microscopic study confirmed the ultrafine nanocrystallite nature of the powder. The thermal stability of the nanopowder studied using thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) shows that the nanopowder has ∼7% weight loss in the temperature range 100-600°C. The UV-Visible diffuse reflectance spectroscopy study carried out on the alumina doped LaFeO₃ ceramics indicate that the sample has narrow optical band gap of ∼2.08 eV. These results show the strong visible-light absorption characteristics of the sample and it perfectly satisfies the band gap requirements of an ideal visible light active photo catalyst. (paper)