Characterization of LaMeO₃ (Me: Mn, Co, Fe) perovskite powders obtained by polymerizable complex method

LaMeO₃ (Me: Mn, Fe and Co) perovskites, obtained by polymerizable complex method at 900 °C for 6 h with grain size of ∼80 nm, were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The Raman active phonons in perovskites crystallized in rhombohedral symmetry - LaMnO_3.15 and LaCoO₃ - and orthorhombic symmetry - LaFeO₃ - were reported. Raman spectra were excited using Ar⁺ laser (wavelength 514.5 nm) with various laser beam powers between 10 and 450 μW on a sample at room temperature. Raman bands were compared to those reported for other similar systems with the orthorhombic and rhombohedral Pbnm structure. The Raman spectra of LaMnO_3.15 and LaCoO₃ were strongly dependent on the laser beam power. Raman spectra obtained for the studied systems are related to many factors as the laser irradiation and the structure of LaMnO_3.15, LaFeO₃ and LaCoO₃ which greatly depends on the method of preparation, particle size, oxygen content, symmetry, temperature or the oxygen partial pressure.