Direct determination of radiation damage profiles in the order-disorder alloy Pt₃Co irradiated with low-energy (500-2500 eV) Ne⁺ ions

A new approach was developed, employing the field-on microscope technique, to determine directly radiation damage profiles in order-disorder alloys; the approach was applied to Pt₃Co. The experiment consisted of irradiating in situ, at 30 K, Pt₃Co specimens with low-energy (500-2500 eV) Ne⁺ ions. The specimens were subsequently dissected on an atom-by-atom basis employing the pulse field-evaporation technique. The latter procedure made it possible to determine the change in the Bragg-Williams long-range order parameter (S) as a function of distance from the irradiated surface. The measurement of δS_d, where the subscript indicates damage, versus distance (x) constituted a radiation damage profile; the depth resolution of this profile was ≈2 A ̊. The mean depth of damage (x_d) varied from ≈9 to 20 A ̊ and the standard deviation or straggling (δ_x) varied from ≈6 to 18 A ̊ as the implantation energy was increased from 500 to 2500 eV. The radiation damage profiles have also been used to determine the effective stopping power of Ne in Pt₃Co.