Magnetic properties of metal endohedral fullerene crystals La@C-82 center dot(Cs-2)(1.5)

We report a magnetic investigation of the endohedral metallofullerene La@C- 82.(CS2)1.5 Firstly, pure La@C-82 was prepared and isolated, then single cr ystals were grown by a slow evaporation method. The crystals were screened by x-ray diffraction measurements and the structure was confirmed to be a b ody centered cubic lattice a=25.62(Angstrom) with space group I-43d. Optica l absorption measurement revealed the compound to be a localised insulating or semi-conducting with a band gap around 2500cm(-1) Temperature dependent EPR and SQUID measurements indicate that the high temperature magnetic beh avior is that of a Curie-Weiss paramagnet, C=0.4(+/-0.1)cm(3)mol(-1) K, whi ch corresponds to a single spin localised on the Cg? cage, Furthermore, a l arge negative Weiss constant, theta = -150(+/-20)K, indicates the presence of strong antiferromagnetic interactions. EPR measurements show a sharp dec rease in the line width occuring below around 160K, indicating a phase tran sition. The Curie moment appears to be lost at temperatures below 80K.