Reactive laser interference patterning on titanium and zinc in high pressure CO₂

Area of Science:

• Materials Science
• Surface Engineering
• Laser-based Manufacturing

Background:

• Direct laser interference patterning (DLIP) is a key technique for creating micro-nano periodic structures.
• Supercritical carbon dioxide (CO2) offers unique solvent properties for advanced material processing.

Purpose of the Study:

• To investigate the efficacy of DLIP using high-pressure, supercritical, and liquid CO2 for patterning titanium and zinc.
• To characterize the resulting surface structures and chemical compositions.
• To explore the potential of pressurized CO2 as a reactive environment for DLIP.

Main Methods:

• Four-beam DLIP was employed to pattern titanium and zinc targets in supercritical and liquid CO2.
• Surface morphology was analyzed using Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM).
• Chemical composition of the patterned surfaces was determined via X-ray Photoelectron Spectroscopy (XPS).

Main Results:

• Ordered, uniform donut ring patterns with hollow centers and periods just under 3 µm were observed on both titanium and zinc.
• AFM revealed protruding donut rings (approx. 200 nm) with central crevices (300 nm for Ti, 250 nm for Zn).
• XPS confirmed the formation of TiO2, TiC, ZnCO3, and zinc hydroxy carbonate on patterned surfaces, a first for DLIP in supercritical/liquid CO2.

Conclusions:

• DLIP in pressurized CO2 is a viable method for creating micro-nano periodic structures on metals.
• This technique enables reactive patterning, forming novel oxides and carbides on titanium and zinc surfaces.
• Supercritical CO2 presents a promising environment for advanced reactive patterning applications due to its properties.