Atomic Displacemets by Electron Irradiation in Pyrolytic Graphite

概要

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The anisotropic threshold energy for atomic displacements and displacement cascade process in electron-irradiated pyrolytic graphite are studied in the energy range from 0.12 to 1.0 MeV at three different temperatures by observing the a-axis electrical resistivity increases. The threshold energy T_d is represented as T_d(Ψ)= A cos^2 Ψ+B sin^2Ψ+C(1-cos 4Ψ)≡(A,B,C) in eV, where Ψis the angle between the c-axis and the direction. In the 6 and 80 K irradiations T_d is given as a set of(23, 30, 0) and (31, 30, -2) ^+_-2eV. and the cascade obeys the Harrison-Seitz Replacement model for Θ=0°, but obeys the Kinchin-pease model for Θ=90°, where Θ is the angle between the c-axis and the electron . In the 285 K irradiations T_d is either (28, 42, 0)^+_-2 eV, or a set of (28, 42, 0) and (32, 42, -1)^+_-2 eV, and the cascade obeys the Harrison-Seitz (no replacement) model for Θ=0°, 30°, 60°and 90°. The effects of crystal structure, lattice vibrations and thermal annealings are discussed using these results.
1971-12-05