Co-Precipitation Of Fe-Cu Bimetal Oxalates In An Aqueous Solution And Their Thermally Induced Decomposition

This work focuses on the preparation of bimetal Fe-Cu oxalates by a co-precipitation reaction in an aqueous solution and subsequently on their thermally induced decomposition. The formation of solid solutions of Fe-Cu oxalates with various Fe/Cu ratios was studied by energy dispersive X-ray analysis, X-ray powder diffraction, transmission Fe-57 Mossbauer spectroscopy, and scanning electron microscopy. The results suggest that the bimetal Fe-Cu oxalate precipitated in a structure similar to beta-FeC2O4 . 2H(2)O. The maximum relative amount of Cu obtained within the bimetal oxalate was approximately 40 %. However, the single bimetal phase composition was obtained only for a limited range of Fe/Cu ratios. The Fe-rich samples contained also beta-FeC2O4 . 2H(2)O, while the Cu-rich samples were predominantly composed of CuC2O4 . nH(2)O and contained much lower amounts of Fe than expected. The thermal decomposition of the prepared oxalate with the nominal Fe/Cu ratio of 65/35 was studied by in-situ X-ray powder diffraction in combination with ex-situ Mossbauer spectroscopy. The mixing of both metals at the molecular level allowed the preparation of copper ferrite particles at a relatively low temperature of 470 degrees C.