Synthesis of single phase rhombohedral LaNiO3 at low temperature and its characterization

LaNiO3 powder was prepared by gel combustion method using sucrose as fuel. Differential thermogravimetry coupled with differential scanning calorimetry (DTA-DSC) was used to identify the combustion temperature and the weight loss regime. The powders calcined at various temperatures were characterized by X-ray diffractometry (XRD), specific surface area analysis, UV-diffused reflectance spectroscopy (UV-DRS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The XRD data revealed the formation of phase pure rhombohedral LaNiO3 at temperature as low as 750 degrees C without formation of any intermediate compound. Local sintering of the crystallites increased in a monotonic manner when calcination temperature increased. Specific surface area showed a decreasing trend with increase in calcination temperature. Band gap studies in the UV-visible range of the optical spectrum were carried out for the powders calcined at various temperatures. Phase pure rhombohedral LaNiO3 showed no optical absorption in this range. SEM study revealed the porous nature of the calcined powder. (C) 2009 Elsevier B.V. All rights reserved.