HOPG

Highly oriented pyrolytic graphite (HOPG) is a form of graphite characterized by its highly ordered atomic structure. It is produced through the thermal decomposition of gaseous hydrocarbons, such as methane, on a substrate at high temperatures, typically around 2,000–3,000 degrees Celsius. This process results in graphite layers that are nearly perfectly aligned, giving HOPG its distinctive properties.

The atomic arrangement in HOPG consists of graphene sheets stacked parallel to each other with minimal defects. This alignment contributes to its exceptional electrical conductivity, thermal stability, and mechanical strength. The material is often used as a substrate in scientific research, particularly in fields like surface science, materials characterization, and nanotechnology.

HOPG is commonly employed in techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS) due to its smooth, flat surface. Its low surface roughness and chemical inertness make it ideal for studying interactions at the atomic or molecular level. Additionally, HOPG is used in semiconductor manufacturing, as an electrode material, and in certain high-temperature applications where its thermal and electrical properties are advantageous.

The quality of HOPG is often categorized by its basal plane resistivity, with lower values indicating higher crystallinity. Commercial grades vary in terms of surface smoothness and defect density, influencing their suitability for specific applications. While HOPG is relatively stable under normal conditions, it can degrade under extreme oxidation or mechanical stress. Proper handling and storage are recommended to maintain its structural integrity.