Kinetics of Thermal Decomposition of Yttrium and Samarium Hydroxides and Sm(OH)3@Y(OH)3 Compound with a Core–Shell Nanostructure

• Published in: Russian journal of general chemistry 2021-07, Vol.91 (7), p.1368-1378
• Main Authors: Sotnikov, A. V., Bakovets, V. V., Plyusnin, P. E.
• Format: Article
• Language: English
• Subjects: Activation energy; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Core-shell structure; Correlation coefficients; Dehydration; Heat treatment; Hydrates; Hydroxides; Kinetic equations; Kinetics; Nanostructure; Phase transitions; Rare earth elements; Samarium; Thermal decomposition; Yttrium; Yttrium compounds
• ISSN: 1070-3632; 1608-3350
• DOI: 10.1134/S107036322107015X

The decomposition mechanisms of hydrated hydroxides of rare-earth metals Sm(OH) 3 ·(H 2 O) gel · n H 2 O and Y(OH) 3 ·(H 2 O) gel · n H 2 O, and also compound [Sm(OH) 3 ·(H 2 O) gel · n H 2 O] q @[Y(OH) 3 ·(H 2 O) gel · n H 2 O] p with a core–shell nanostructure were studied. In the course of the thermal treatment of hydroxides in the range of 25–900°C, stages of successive phase transformations were observed. The Avraami-Erofeev model of topochemical reactions describes the formation of phases in the systems under study with the highest correlation coefficient. The kinetics of successive dehydration and dehydroxylation of the above compounds was studied, kinetic equations of the topochemical reactions were presented, and apparent activation energies and the preexponents of the reactions were calculated. The activation energy for polycondensation of the compound with a core-shell nanostructure is lower than that of individual hydrates of samarium and yttrium hydroxides.