POSITRON SPECTROSCOPY OF LIQUID CRYSTALLINE ORGANIC MATERIALS CONTAINING C60 FULLERENES

Free-volume structure in the lanthanum salt of laurinic acid in crystalline and liquid-crystalline states and an effect of dissolved 60 molecules on the mean nanovoid radius and concentration were studied by means of the positron annihilation technique. La(C12 25COO)3 clathrate compound with dissolved 60 molecules was obtained, which is thermodynamically more stable than a simple mixture of components. Increased mean nanovoid radius (from 0.28 to 0.39 nm) after the inclusion of C60 molecules and concomitant decrease of the positronium annihilation rate by a factor of 2.7 indicate the decrease of the smallest nanovoid concentration.