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

Pr(NO3)(3). 6H(2)O was used as a precursor to produce PrO1.833 at 600 degre esC in an atmosphere of static air. Thermal processes occurred were monitor ed by means of thermogravimetry, differential thermal analysis and mass spe ctrometry. IR-spectroscopy and X-ray characterized the intermediates and fi nal solid products. The results showed that, Pr(NO3)(3). 6H(2)O decomposes through ii endothermic weight loss processes. Five dehydration steps occurr ed at 130, 180, 200, 230 and 250 degreesC, leading to the formation of crys talline nitrate monohydrate. Which decomposes to Pr(NO3)(2) at 340 degreesC . The latter, decomposes to PrO1.833 at 465 degreesC, via four different in termediates PrO(NO3) at 430 degreesC, and nonstoichiometric unstable, PrO0. 25(NO3)(2.5) at 362 degreesC; PT(O)(0.5)(NO3)(2) at 382 degreesC and Pr(O)( 0.75)(NO3)(1.5) at 400 degreesC. The gaseous decomposition products identif ied 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 m(2)/g. (C) 2001 Elsevier Science B.V. All rights reserved.