Superconductivity of Fullerides AnHgxC60 (A = K,Rb,Cs; n = 2,3) Synthesized from Amalgams

The fullerides A(n)Hg(x)C(60) (A - K,Rb,Cs; n - 2,3; x<1) have been synthesized by a new method using liquid alloys of metals with mercury (amalgams). It was found that the fulleride K2HgxC60 is superconductor with transition temperature T-c = 22 K that exceeds T-c for K3C60 (19 K). The fulleride K3HgxC60 is not superconductor and has monoclinic crystal lattice. The fullerides RbnHgxC60 (n = 2,3) are superconductors with T-c = 24-25 K that is less than T-c = 28 K for Rb3C60. The fullerides with composition CsnHgxC60 (n = 2,3) are not superconductors and crystallize in orthorhombic lattices. The density of electronic states at Fermi energy was estimated from EPR data.