Point-Defect Studies in Platinum by Electron Irradiation at Low Temperatures. I. Defect Production

The electrical resistivity increase per unit electron flux (damage rate) of 99.999%-pure 0.0002-in.-thick platinum foils was measured as a function of incident electron energy from 1.3 to 2.1 MeV near 9^∘{}K. Reasonable agreement between the theoretical displacement cross section, calculated with a unit displacement probability, and experimental data is achieved with an effective threshold displacement energy of 36 eV and a Frenkel resistivity of 6×{}10^-4{Ω} cm per unit fractional concentration Frenkel pairs. The ratio of the damage rate of platinum to that of gold is nearly independent of the electron energy for 45 eV<Tₘ<72 eV and decreases rapidly to zero for Tₘ<45 eV, where Tₘ is the maximum energy imparted to a lattice atom by a bombarding electron. These results are interpreted to indicate that indirect displacement processes occur in both metals near threshold.