Published online by Cambridge University Press: 21 February 2011
The growth of single crystals of Bi2+xSr2−yCuO6±δ from alkali chloride fluxes, typically sodium chloride is reported. Electronic properties of the resultant crystals are controlled by the melt composition and the partial pressure of oxygen during growth. Superconducting crystals with Tc's near 10K are obtained under low oxygen partial pressures from melts which are strontium-rich. Measurements of transport, tunneling and magnetoconductivity in nonsuperconducting crystals show two-dimensional localization within the CuO2 planes. Superconductivity occurs only when transport perpendicular to the planes gives rise to extended states in three dimensions.