POLYMERIZATION AND PHASE DIAGRAM OF SOLID C70 AFTER HIGH-PRESSURE-HIGH-TEMPERATURE TREATMENT

Abstract For the first time investigations of structure and physical properties of C 70 after treatment at 4 ≤ P ≤ 12.5 GPa and 300 ≤ T ≤ 1770 K were carried out by X-ray, Raman and infrared spectroscopy. The results are plotted in a ( P , T ) diagram. The new superhard 3D-polymerized tetragonal phase has been found at P ≥ 9.5 GPa. The superhard disordered state of samples produced from C 70 at 12.5 GPa with a hardness close to that of (100)-face diamond has also been found.