Thermal genesis course and characterization of praseodymium oxide from praseodymium nitrate hydrate

Pr(NO3)3·6H2O was used as a precursor to produce PrO1.833 at 600°C in an atmosphere of static air. Thermal processes occurred were monitored by means of thermogravimetry, differential thermal analysis and mass spectrometry. IR-spectroscopy and X-ray characterized the intermediates and final solid products. The results showed that, Pr(NO3)3·6H2O decomposes through 11 endothermic weight loss processes. Five dehydration steps occurred at 130, 180, 200, 230 and 250°C, leading to the formation of crystalline nitrate monohydrate, Which decomposes to Pr(NO3)2 at 340°C. The latter, decomposes to PrO1.833 at 465°C, via four different intermediates PrO(NO3) at 430°C, and nonstoichiometric unstable, PrO0.25(NO3)2.5 at 362°C; Pr(O)0.5(NO3)2 at 382°C and Pr(O)0.75(NO3)1.5 at 400°C. The gaseous decomposition products identified by mass spectroscopy were water vapor and nitrogen oxides (NO, NO2 and N2O5). The activation energy was determined nonisothermally for the thermal processes monitored throughout the decomposition course. The final product PrO1.833 has a surface area of 46.3 m2/g.