Synthesis, structure parameter and reaction pathway for spinel-type Co2SnO4

Co2SnO4 powders with the spinel structure were successfully obtained by the sol–gel method using Co(NO3)2·6H2O and SnCl4·5H2O as raw materials, followed by calcining at 900 and 1500 °C for 1 h. Characterization by XRD and SEM showed that at 900 °C, crystalline spinel accompanied by Co3O4 and SnO2 is obtained, while at 1500 °C homogeneous single-phase spinel powders are synthesized. Analysis by X-ray diffraction (XRD) aided by the refinement method of Rietveld allowed phase quantification and determination of the spinel lattice parameter (8.464 ± 0.005 Å). A reaction pathway is put forward based on a thermal analysis using simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). The proposed mechanism suggests that spinel is formed by the reaction between SnO2 (formed from SnCl4) and CoO which in its turn is produced during the decomposition reaction of Co3O4 into CoO and O2. Co3O4 on the other hand, is formed previously from Co(NO3)2.

► Co2SnO4 is obtained by sol-gel with Co(NO3)26H2O+SnCl45H2O, 1500 °C/1 h calcining.
► At 900 °C, the crystalline spinel obtained is accompanied by Co3O4 and SnO2.
► Spinel is formed above 900 °C by reaction between SnO2 (formed from SnCl4) and CoO.
► CoO is produced together with O2 during the decomposition reaction of Co3O4.
► A reaction pathway/mechanism is put forward based on TGA and DSC thermal analyses.