Growth and characterization of Bi2+xSr2-xCuO6+δBi2+xSr2-xCuO6+δ single crystals

High-quality Bi2+xSr2-xCuO6+δ(00.05x>0.05 are in the underdoped level. The structure of these crystals was investigated by X-ray diffraction. The evolution of c-axis lattice parameters with varied x   is displayed, which is strongly associated with the behavior of TcTc. The crystals exhibit superconducting transitions with Tc=9Tc=9–0.8K for the samples with x=0.05x=0.05–0.200.20, while for samples with x=0.25x=0.25 and above no superconductivity was discovered down to 1.6 K. The resistivity of samples with x=0.31x=0.31, 0.40 and 0.50 exhibits a drastic divergence as temperature approaches 0 K.