Radiation damage, its recovery and platinum behavior and lattice location in ion bombarded MgO and Al2O3as used for catalytic studies

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Abstract
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 × 1015 and 8 × 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 1300°C 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 ∼650°C, the temperature of the phase change to the recrystallized state. At temperatures in excess of 900°C, 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.