High-Temperature and High-Speed Atomic Force Microscopy Using a qPlus Sensor in Liquid via Quadpod Scanner and...

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Studying liquid-solid interfaces at the atomic level is crucial for understanding phenomena like corrosion, catalysis, and phase transitions.
• Traditional atomic force microscopy (AFM) techniques are limited in their ability to image these interfaces at elevated temperatures due to thermal drift and sensor limitations.

Purpose of the Study:

• To develop and demonstrate a high-temperature, high-speed AFM system capable of atomic-resolution imaging of molten metal/solid interfaces above 200°C.
• To investigate the surface structure of molten Gallium (Ga) on a solid PtGax substrate at elevated temperatures.

Main Methods:

• Development of a high-speed Quadpod scanner designed for tip-scanning and accommodating a high-mass qPlus sensor (2.3 g) to improve thermal drift tolerance.
• Implementation of a Hybrid-Loop frequency demodulation technique for low-resonant-frequency sensors, offering a wider bandwidth compared to conventional phase-locked loops.
• Utilizing a high-temperature, high-speed AFM system equipped with a qPlus sensor to image the molten Ga/PtGax interface at approximately 210°C.

Main Results:

• Achieved atomic-resolution imaging of the molten Ga/PtGax interface at ~210°C.
• Observed a low-symmetry surface with an oblique lattice and superstructure at 210°C, contrasting with the primitive rectangular lattice seen in the room-temperature sample.
• Demonstrated the capability of the developed AFM technique to visualize non-aqueous liquid/solid interfaces above 200°C at atomic resolution.

Conclusions:

• The developed high-temperature, high-speed AFM technique successfully enables atomic-resolution imaging of molten metal/solid interfaces above 200°C.
• The observed structural changes at the molten interface highlight the dynamic nature of liquid-solid interactions at high temperatures.
• This advancement opens possibilities for in-situ studies of processes like injection molding, soldering, and the development of liquid-metal catalysts.