Optimal parameters for synthesizing single phase spinel-type Co2SnO4 by sol–gel technique: Structure determination and microstructure evolution

• Co2SnO4 powders were synthesized by the sol–gel method.
• At 900 °C, the crystalline spinel obtained is accompanied by Co3O4 and SnO2.
• A high percentage (94.7%) of this phase is obtained at 1300 °C for 1 h.
• The conditions to obtain 100% Co2SnO4 homogeneous single-phase is 1400 °C for 5 h.
• The X-ray Rietveld method was applied to analyze all powders.

Powder samples of spinel Co2SnO4 were successfully synthesized by the sol–gel technique at three different temperatures: 900, 1300 and 1400 °C for 1, 5 and 8 h. XRD patterns and SEM images provided evidence of the structural and morphological evolution during the formation of the spinel phase. Thermal analysis confirmed the reaction pathway in which the 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 [formed from Co(NO3)2] into CoO and O2. Determination of the quantitative phase at each combination of temperature and time as well as the lattice parameters was possible by the Rietveld refinement. The optimal parameters for the complete formation of Co2SnO4 are 1400 °C for 5 h. It is worth mentioning that at 1300 °C for 1 h, the percentage of the spinel obtained is considerably high (94.7%).