Preparation and characterization of Rb3C60 bulk single crystals

Rb3C60 crystals with a size of several tenths of a millimetre were prepared by doping C60 crystals in rubidium vapour. Experiments with different annealing times and various annealing temperatures and temperature gradients were performed to assess the optimal conditions for homogeneous doping. The crystals were characterized by ac magnetization measurements. Doping at 463 K with 10% excess of rubidium and annealing at 685 K for 27 days were found to produce the best crystals with almost 100% of the superconducting Rb3C60 phase.