Characterization of KrF Excimer Laser Ablation of Cadmium in Different Liquids for Biomedical and Industrial Applications

Abstract

Liquid-assisted laser ablation (LALA) has gained substantial attention as a method that can achieve desired chemical and physical properties. The fabrication of carbides (CdCO3), oxides (CdO), and hydro-oxides (Cd(OH)2) on Cd surfaces make them more useful in industrial and biomedical applications due to the enhancement of their physical properties. For this purpose, LALA of Cadmium (Cd) is performed using a KrF Excimer laser (248 nm, 20 ns) at varying numbers of pulses from 500 to 2000 at constant fluence (3.6 Jcm−2) in deionized water (DI) and ethanol. A comparison of the ablation behavior of Cd in DI water and alcohol (ethanol) environments is discussed in the present work. The surface structuring and enhancement of mechanical properties are also discussed in correlation with the changes produced in its crystallinity due to the increase in the chemical reactivity of Cd in both ambient environments. The surface features, chemical composition, structural and compositional analysis, and mechanical properties of irradiated targets are evaluated using a Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Fast Fourier Transform Infrared spectroscopic (FTIR), Energy Dispersive X-ray Spectroscopy (EDS), and a Nano-hardness tester. Pores, cavities, hillocks, wave-like ridges, nanoparticles, flake-like structures, and periodic surface structures are distinguished features on the Cd surface after irradiation. However, the density and size of pores and cavities are higher in water, whereas ethanol is favorable for the growth of craters and ripples. These features are attributable to various thermal and chemical phenomena induced by laser heating at the solid–liquid interface. Ethanol-assisted ablation is more favorable for enhancing the hardness of Cd as compared to DI water-assisted ablation due to the presence of maximum compressive stresses and minimum crystallite size (C.S.) caused by the diffusion of carbon into the target surface.