EFFECT OF FUEL TO OXIDANT RATIO ON STRUCTURAL AND OPTICAL PROPERTIES OF LaAlO3 NANOPARTICLES

Lanthanum Aluminum Oxide nanoparticles have been synthesized by an auto-combustion method for different oxidant to fuel (O/F) ratios (0.5, 1.0 and 1.5). Lanthanum nitrate and Aluminum nitrate were used as oxidants, Citric acid as fuel and Ammonia as buffer to adjust the pH of the solution. Crystallinity and crystalline phases of the prepared samples were analyzed using X-ray diffraction and the reflection planes (100), (110), (111), (200), (210), (211), (220), and (300) revealed the rhombohedral phase as comparable to the JCPDS standards (Card No. 85-0848). FTIR spectra again confirmed the single phase formation of compound by the noticeable metal-oxygen (AlO6 octahedra) ligand formation band in the lower frequency region at about 665 cm-1. In the higher frequency region, the band appeared at 440 cm-1 was assigned to the La-O coordination of the samples. Optical measurement revealed absorption in the low wavelength region that corresponds to the optical absorption edge, 4.95eV, 4.77eV, 4.88eV respectively for the LaAlO3 samples prepared for three different F/O ratios.