Formation energy of alkali-metal-doped fullerite compounds A6C60

The formation energy, [Delta]H[sub f], of fullerite intercalation compounds A[sub n]C[sub 60] with A = Na, K, Rb, and Cs and n = 6 is measured using differential scanning calorimetry. The alkali metals, K, Rb, and Cs react with C[sub 60] powders readily and directly form the bcc A[sub 6]C[sub 60]. [Delta]H[sub f] values are found to be [minus]28, [minus]39, [minus]40, and [minus]47 kcal/mol per alkali metal for Na, K, Rb, and Cs, respectively. The activation energy of diffusion of the alkali metals Rb and Cs in the corresponding A[sub 6]C[sub 60] compound is evaluated to be approximately 30 kcal/mol. 25 refs., 4 figs., 1 tab.