Thermal decomposition study of erbium oxalate hexahydrate

The thermal decomposition of erbium oxalate hydrate (Er2(C2O4)3·6H2O) till 900°C, in air and nitrogen, is investigated by nonisothermal gravimetry and differential thermal analyses. The activation energy (ΔE) is determined for each thermal decomposition step. The gaseous decomposition products are identified by infrared (IR)-spectroscopy. Intermediate and final solid products are characterized by IR-spectroscopy and X-ray diffraction (XRD). The results indicate that, in air atmosphere, following a stepwise dehydration at 90–370°C, the anhydrous product was noncrystalline and thermally unstable. An oxycarbonate Er2O2CO3 is obtained at 450°C which decomposes near 600°C into crystalline Er2O3. The atmosphere has no affect on the decomposition pathway. The oxide proportion and crystallinity improved on increasing the temperature to 800°C. The volatile decomposition products were water vapor and carbon oxides.