Metal-ceramic composites: a study of small metal particles (divided metals)

Abstract

Metal particles in Pt/1bAl₂O₃ and Ni/1bAl₂O₃ composites prepared by the reduction of the xerogels have been investigated by high resolution electron microscopy and X-ray diffraction. The alumina phase is essentially amorphous while the metal particles are crystalline. The average size of the metal particles increases with the metal content in the composites. Pt atoms exhibit a greater tendency to form metal clusters than the Ni atoms. At low metal concentrations (≲0.25 wt%), the number of atoms in the metal particles is in the range 100-400. Lattice resolution of the metal particles has been observed in HREM images. The cubic phase of ZrO₂ is stabilized in Ni/1bZrO₂ composites, the stability increasing with the Ni content.