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Abstract

High-purity C₆₀ has been studied by in situ X-Ray Diffraction (XRD). Between 300 and 900 K, the volume thermal expansion coefficient isα _v = 4.57(4) × 10⁻⁵ K⁻¹ with no observable deviations from linearity. Recrystallization is activated atT ≥ 600 K, as observed by the fast ( < 5 s) and slow ( > 10 min) variations in low-index Bragg intensities. At lower temperatures, thermal desorption of molecular oxygen at ≈420 K is accompanied with a step-wise increase of the 111-Bragg reflection intensity, but with no measurable change of the lattice parameter. The twin fault density has first been determined using high-resolution XRD. The (winning probability is 0.8%. Crystallites show a ± 0.3° intrinsic mosaic spread. Mechanical milling in acetone and in air increases the twinning probability to 1.8 and 3.1%, respectively.