P. Kokkonen, L. Lajunen, L. Palmu
Jul 15, 1987
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Journal
Thermochimica Acta
Abstract
Abstract The thermal decomposition of the dysprosium and erbium salicylates, and 5-chloro and 5-bromosalicylates was studied by TG, DSC, IR and MS techniques. The various dysprosium salicylates were precipitated from aqueous solution as dihydrates and the corresponding erbium salicylates as tetrahydrates. The TG curves show four steps of decomposition. The decomposition reaction mechanism of the complexes was studied by analyzing the intermediate products with mass and IR spectrometry. The first three stages for all the complexes are associated with the dehyration, the release of free ligand acid and the release of ligand acid by decarboxylation. The 5-chlorosubstituted salicylato complexes were thermally more stable than unsubstituted or 5-bromosubstituted salicylato complexes. For each complex, the first two steps are endothermic, while the third step is strongly exothermic. The oxides, Ln2O3 were obtained in the temperature range 938–1023 K. The temperature for oxide formation seems to follow the order salicylic acid > 5-chlorosalicylic acid > 5-bromosalicylic acid.