Thermogravimetric study of the scandium nitrate hexahydrate thermolysis and computer modeling of intermediate oxynitrates

• Published in: Journal of thermal analysis and calorimetry Vol. 119; no. 2; pp. 1073 - 1079
• Main Authors: Melnikov, P., Nascimento, V. A., Arkhangelsky, I. V., de Oliveira, L. C. S., Silva, A. F., Consolo, L. Z. Zanoni
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-02-2015; Springer
• Subjects: Analytical Chemistry; Bonding; Calorimetry; Chemistry; Chemistry and Materials Science; Comparative analysis; Computer simulation; Computer-generated environments; Inorganic Chemistry; Measurement Science and Instrumentation; Monomers; Nitrates; Physical Chemistry; Polymer Sciences; Pyrolysis; Rare earth metals; Scandium; Scandium oxides; Thermal decomposition; Scandium nitrate hexahydrate; Rare earth; Oxynitrates; Thermal decomposition; Computer modeling
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-014-4272-7

The thermal decomposition of scandium nitrate is a complex process, which begins with the simultaneous condensation of 4 mol of the initial monomer Sc(NO
3
)
3
·6H
2
O. The resulting cyclic tetramer Sc
4
O
4
(NO
3
)
4
·2H
2
O gradually loses azeotrope H
2
O–HNO
3
, and an intermediate oxynitrate Sc
4
O
5
(NO
3
)
2
is formed. At higher temperature, this oxynitrate is destroyed leaving behind unstable dimer Sc
4
O
6
which is transformed into scandium oxide. The molecular mechanics method used for comparison of the potential energies of consecutive products of thermal decomposition permits an evaluation of their stability and a proper interpretation of experimental data. The structural modeling was aimed to provide detailed information about the bond lengths and bond angles, filling the gap in what we know about amorphous oxynitrates. The models represent a reasonably good approximation to the real structures.