Crushing C₆₀ to diamond at room temperature

Abstract

C_6o MOLECULES are extremely stable, withstanding hydrostatic pressures of up to at least 20 GPa (ref. 1). It has been proposed that at high pressures they could form a solid harder than diamond². On the other hand, electrical resistivity measurements³ have revealed the formation of an insulating phase above 20 GPa, which was attributed to the low-symmetry state found in X-ray diffraction studies under nonhydrostatic compression¹. Here we report that rapid, nonhydrostatic compression of C₆₀ to pressures of 20 ±5 GPa transforms it instantaneously into bulk polycrystal-line diamond at room temperature. Our measurements place a limit on the stability of the C₆₀molecular phase under nonhydrostatic pressure. The high efficiency and fast kinetics at room temperature suggest the possibility of using this transformation for fabrication of industrial diamonds.