Oxidation of nanophase tin particles

Abstract

Tin particles of nanometer size have been synthesized by the gas condensation method using helium as the convection gas. In order to study oxidation behaviors of the nanophase tin powder, the changes in morphology and crystal phases were investigated during heat treatment in air. The as-synthesized powder was oxidized to both the stable tetragonal SnO2 and the non-stable orthorhombic SnO2 which is known to form at extremely high pressure. An intermediate annealing at 225 degrees C for 20 hours gave rise to the oxidation induced amorphization of nano-sized tin particles. The formation of the amorphous tin oxide was explained by suppressed nucleation of crystalline oxides in nano-sized particles. The amorphous tin oxide was transformed into the tetragonal SnO2 through crystallization. (C) 1999 Acta Metallurgica Inc.