  We report the crystal growth and structural, magnetic, conductivity, and
specific heat investigations of Rb(1-x)Fe(2-y)Se2 single crystals with varying
stoichiometry prepared by self-flux and Bridgman methods. The system exhibits a
strongly anisotropic antiferromagnetic behavior below 400 K. For 1.53 <2-y< 1.6
superconductivity is found, whereas for Fe concentrations 2-y< 1.5 and 2-y> 1.6
insulating and semiconducting behavior is observed, respectively. The sharpest
transition to the superconducting state and the highest transition temperature
T_c of 32.4 K is found for compositions close to Rb2Fe4Se5. A critical current
density j_c of 1.6*10^4 A/cm^2 (at 2 K) is obtained in the superconducting
samples with the highest diamagnetic response. In these samples additional
intense x-ray reflexes appear, which are incompatible with the tetragonal
symmetry. Upper critical fields H_{c2} of ~250 kOe for the in-plane and 630 kOe
for the inter-plane configurations are estimated from resistivity in magnetic
fields parallel and perpendicular to the c-axis, respectively. In the
non-superconducting samples with the Fe concentration below 1.45 both specific
heat and susceptibility revealed an anomaly at 220 K which is not related to
antiferromagnetic or structural transformations. Comparison with the magnetic
behavior of non-superconducting samples provides evidence for the coexistence
of superconductivity and static antiferromagnetic order.
