Thermal genesis course and characterization of lanthanum oxide

La(NO3)3·6H2O was used as a precursor to produce La2O3 at 650°C in an atmosphere of air. Thermal processes occurred were monitored by means of thermogravimetry, differential thermal analysis, and gas-mass spectrometry. Infrared (IR)-spectroscopy, X-ray diffractometry and scanning electron microscopy characterized the intermediates and final solid products. The results showed that, La(NO3)3·6H2O decomposes through nine endothermic weight loss processes. Five dehydration steps occurred at 90, 105, 150, 175 and 215°C, leading to the formation of crystalline nitrate monohydrate, which decomposes to La(OH)(NO3)2 at 410°C. The latter, decomposes to La2O3 at 640°C, via two different intermediates; LaO(NO3) at 440°C, and non-stoichiometric unstable, La(O)1.5(NO3)0.5 at 570°C. The gaseous decomposition products as identified by gas-mass spectroscopy were water vapor, nitric acid and nitrogen oxides (NO, NO2 and N2O5). The final product La2O3 has a large crystalline containing pores, voids and cracks, with a surface area of 23 m2 g−1. Also it possessed Lewis acidic and basic sites, as indicated by Pyridine adsorption.