Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy, Tb, Gd, Eu and Sm)

• Published in: Journal of thermal analysis and calorimetry 2014-02, Vol.115 (2), p.1253-1264
• Main Author: Grivel, J.-C.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-013-3467-7

The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes place below 120 °C, all salts decompose into dioxycarbonates with simultaneous release of CO 2 and C 2 H 5 COC 2 H 5 (3-pentanone) between 250 and 460 °C. However, whereas the anhydrous Dy-, Tb-, and Gd-propionates appear to transform into RE 2 O 2 CO 3 (rare earth [RE] = Dy, Tb, Gd) in a single step, an intermediate stage involving a RE 2 O(C 2 H 5 CO 2 ) 4 composition was evidenced in the case of the Eu- and Sm-propionates. For all compounds, further decomposition of RE 2 O 2 CO 3 into the corresponding sesquioxides (RE 2 O 3 ) is accompanied by the release of CO 2 . The thermal decomposition of Dy- and Tb-propionates occurs entirely in the solid state. In contrast the dehydrated Gd-, Eu-, and Sm-propionates melt at increasingly higher temperatures. Evidence for recrystallization was found in conjunction with the onset of decomposition of these three propionates.