High-Temperature and High-Pressure Synthesis of High-Purity Rhombohedral C₆₀ Polymer

Rhombohedral C₆₀ polymer holds significant potential for applications in two-dimensional materials and catalysis, yet the synthesis of high-purity, high-quality rhombohedral C₆₀ remains challenging. In this study, rhombohedral C₆₀ polymer was successfully synthesized under conditions of 6 GPa and 650 ℃. The obtained sample was confirmed to be a high-purity two-dimensional rhombohedral phase through characterization techniques including X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and aberration-corrected transmission electron microscopy. The effects of pressure and temperature (6–10 GPa, 650–800 ℃) on the polymerization of C₆₀ were investigated, clarifying the phase boundary between the rhombohedral phase and disordered amorphous carbon clusters. Variable-temperature Raman spectroscopy revealed that the rhombohedral C₆₀ polymer remains stable up to about 350 ℃, beyond which it depolymerizes and reverts to the original face-centered cubic C₆₀ molecules. This work provides a clear processing window for the synthesis of high-quality rhombohedral C₆₀ polymer, laying an experimental foundation for its further application in functional materials.