Effect of target temperature during carbon implantation on the composition and electrochemical properties of iron surface layers

Abstract

A study was made of the dependence of the properties of iron surface layers on target temperature during carbon implantation. Implantation of C + ions into pure iron sheets was carried out with a dose of 2 × 10 17 ions cm -2 at an energy of 100 keV. The target temperatures during implantation were kept at approximately -100, 20 and 200 °C. The composition and structure of the implanted layers were investigated by X-ray photoelectron spectroscopy, X-ray diffraction and laser Raman spectroscopy. Multisweep cyclic voltammetry was utilized to evaluate the anodic dissolution properties of carbon-implanted iron electrodes. The carbon distribution for specimens implanted at -100 and 20 °C shows a gaussian-like shape except near the top-surface, and the distribution for implantation at 200 °C is trapezoidal. The carbon atoms in the implanted layers combine with iron and carbon itself to form C-Fe and C-C bonds. The higher temperature during implantation produces a larger amount of C-Fe bonds, and in contrast, the lower temperature implantation results in the formation of a larger amount of C-C bonds. The implanted iron electrode at a target temperature of -100 °C shows strong suppression of the anodic dissolution of iron. The relations between the electrochemical properties and surface microscopic characteristics are discussed.