Radiation damage, its recovery and platinum behavior and lattice location in ion bombarded MgO and Al2O3 as used for catalytic studies

Channeling and back-scattering techniques were used to study single crystals of α-Al2O3 and MgO following bombardment with Pt-(or Xe-)ions of 30 keV energy and doses between 9 x 1015 and 8 x 1016 ions/cm2, as used for catalytic investigations. The MgO crystals showed saturation damage after implantation with the lower dose. Damage recovery proceeded progressively with increasing temperature and was not complete before 13000C was reached. The Pt formed coherent precipitates. In contrast, a quasi-amorphous zone was formed on ion bombarded Al2O3. Outdiffusion of the impurity and recovery of the bombardment damage started at approximately 6500C, the temperature of the phase change to the recrystallized state. At temperatures in excess of 9000C, the Pt precipitated into small single crystal grains of near spherical shape. The results can be used to interpret the catalytic behavior of the systems Pt/single crystalline support. (author)