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 infl uence of the calcium salt as well as the solvent used to dissolve the tin s alt is discussed. Three methods have been employed to prepare the xerogel: a rapid evaporation of the solution, a refluxing of the solution and an hyd rothermal preparation. The coupling of X-ray diffraction and Sn-119 Mossbau er spectroscopy allows ro identify the different phases and to optimise the synthesis parameters. In addition, the Mossbauer spectra allowed to identi fy the various sites of tin and their evolution with annealing temperature. An almost pure (95%) tin sphene can be prepared as monodisperse spherical powders. (C) 2000 Elsevier Science Ltd. All rights reserved.