Superconductivity in single-phase ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{9-x}$ and thermoelectric power measurement

Single-phase ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{9-x}$ has been synthesized and characterized. Although x-ray diffraction shows only the ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{9-x}$ phase which has an orthorhombically distorted perovskite structure, resistance measurements reveal two transition temperatures, $T_{c1\mathrm{}}=95.5\mathrm{}$ K and $T_{c2\mathrm{}}=93\mathrm{}$ K. Thermoelectric power measurements indicate that ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{9-x}$ is of $n$ type. Strong enhancement and unusual temperature dependence for the "phonon-drag" effect which might be indicative of an unusual superconducting mechanism in this material have been observed.