Effect of ageing on Sn₆O₄(OH)₄ in aqueous medium—simultaneous production of SnO and SnO₂ nanoparticles at room temperature

Precipitation is one of the dominant techniques for producing tin oxide which requires calcination of the interim tin oxide hydroxide (Sn₆O₄(OH)₄) precipitate at different temperatures to render the requisite oxide states. In this study, we mitigated the necessity for calcination through simple ageing of the the as-synthesized Sn₆O₄(OH)₄ at room temperature (25 °C) in aqueous medium. Ageing for 12 days resulted in phase transition of the interim precipitate and production of discernible layers of black stannous oxide (SnO) and yellow stannic oxide (SnO₂) along with the originally formed white layer of Sn₆O₄(OH)₄ within the same aqueous medium. The phases of tin oxide was confirmed after extracting individual layer and assessing them through X-ray analysis. Thermogravimetric analysis for the as-obtained stannous oxide established its thermal stability up to around 410 °C. Additionally, Field Emission Scanning Electron Microscopy studies performed on the SnO nanoparticles revealed their dimension to be within 25–30 nm range. The mechanisms for SnO and SnO₂ formation through ageing has been delineated.