HYDROLYTIC CONDENSATION OF TIN(IV) ALKOXIDE COMPOUNDS TO FORM PARTICLES WITH WELL-DEFINED MORPHOLOGY

The sol-gel-type condensation of tin(IV) ethoxide [Sn(OEt)4]n (where OEt is ethoxide) under basic conditions produced spherical, submicrometer-sized tin(IV) oxide (cassiterite) particles. Transmission electron microscopy and powder X-ray diffraction data indicated that the grain size was approximately 20 to 30 angstrom (2 to 3 nm). The mixed-metal alkoxide compound [ZnSn(OEt)6] was hydrolyzed under analogous conditions to give either spherical or octahedral submicrometer-sized crystalline particles of ZnSn(OH)6 depending on the solvents used. These data demonstrated that the stoichiometry of the mixed-metal alkoxide precursor was retained during condensation. Thermal treatment of ZnSn(OH)6 resulted in crystallization of ZnSnO3 at approximately 676-degrees-C. At neutral pH, hydrolysis of [ZnSn(OEt)6] resulted in formation of a high surface area (261 m2/g) amorphous powder.