Systematic study of phase-formation and lattice structure of La_0.9Sr_0.1Fe_1-xMo_xO₃ synthesized through the sol-gel method

In this paper, we investigated the phase formation and lattice structure of La_0.9Sr_0.1Fe_1−xMo_xO₃ (x = 0.0, 0.1, 0.2, and 0.3) (LSFMO), which we have synthesized through the sol-gel method. The heat treatment has been performed to study the chemical and physical reaction during the processes. The formation and structural evolution of the LSFMO phase were systematically investigated through scanning electron microscopy (SEM), x-ray powder diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and Raman scattering spectroscopy. The SEM images revealed that the grains basically consisted of several crystallites. The XRD showed organic phases (C₆H₁₂O₄ and H₂N₂O₂) upon heating at 175 °C and 400 °C, which then gave way to the LSFMO phase after calcination at 900 °C. The lattice structure is orthorhombic and the lattice parameters and crystal distortion increase upon the addition of Mo. The results of the DTA exhibited two exotherms at temperatures near 300 °C and 450 °C, which were interpreted as the temperatures at which the organic phases decomposed. The TGA results confirmed weight loss due to the decomposition of the organic phases during the formation of the LSFMO phase. The Raman-active phonon modes provide evidence for the lattice distortion with increasing Mo doping.