Thermal decomposition of lutetium nitrate trihydrate Lu(NO3)(3)center dot 3H(2)O

摘要

The thermal decomposition of lutetium nitrate starts with essentially a process of dehydration of the initial monomer Lu(NO3)(3)center dot 3H(2)O with further condensation into a hexamer Lu6N18O54 center dot 6H(2)O. The latter decomposes in four steps with release of water, azeotrope 68% HNO3-32% H2O, nitric acid, nitrogen dioxide and oxygen. The resulting intermediate compounds are lutetium oxynitrates Lu6N4O19 and Lu6N2O14. After complete denitrification at high temperatures, they are converted into unstable trimer Lu6O18 which is destroyed leaving behind lutetium oxide. All mass losses are accounted for, step by step. The intermediates were characterized using thermal analysis, infrared spectroscopy and X-ray diffractometry. The models of intermediate oxynitrates obtained with the molecular mechanics technique represent a reasonably good approximation to the real structures.