Tin sphene micron-sized powders

A new sol–gel route is used to prepare tin sphene micron-sized powders. An aqueous solution of silicic acid is used as the silicon precursor. The influence of the calcium salt as well as the solvent used to dissolve the tin salt is discussed. Three methods have been employed to prepare the xerogel: a rapid evaporation of the solution, a refluxing of the solution and an hydrothermal preparation. The coupling of X-ray diffraction and 119Sn Mössbauer spectroscopy allows to identify the different phases and to optimise the synthesis parameters. In addition, the Mössbauer spectra allowed to identify the various sites of tin and their evolution with annealing temperature. An almost pure (95%) tin sphene can be prepared as monodisperse spherical powders.