Anisotropic superconducting properties of aligned (Bi,Pb)2Can−1Sr2CunO2n+4+δpowders (n=1,2,3) withTc=32, 94, and 110 K

The anisotropic superconducting properties of aligned powders embedded in epoxy for bismuth copper oxides with the compositions (${\mathrm{Bi}}_{1.6}$ ${\mathrm{Pb}}_{0.4}$)(${\mathrm{Sr}}_{1.5}$ ${\mathrm{La}}_{0.5}$)${\mathrm{CuO}}_{6+\mathrm{\delta }}$ (n=1, ${\mathit{T}}_{\mathit{c}}$=32 K), ${\mathrm{Bi}}_2$ ${\mathrm{Ca}}_{1.2}$ ${\mathrm{Sr}}_{1.8}$ ${\mathrm{Cu}}_2$ ${\mathrm{O}}_{8+\mathrm{\delta }}$ (n=2, ${\mathit{T}}_{\mathit{c}}$=94 K), and (${\mathrm{Bi}}_{1.85}$ ${\mathrm{Pb}}_{0.15}$)${\mathrm{Ca}}_{2.2}$ ${\mathrm{Sr}}_{1.8}$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{10+\mathrm{\delta }}$ (n=3, ${\mathit{T}}_{\mathit{c}}$=110 K) are reported. These c-axis-aligned samples were prepared in a 9.4-T applied magnetic field at room temperature. The temperature dependence of the anisotropy ratio ${\mathrm{\chi }}_{\mathit{c}}$(T)/${\mathrm{\chi }}_{\mathit{a}\mathit{b}}$(T) in the superconducting state is derived from both zero-field-cooled and field-cooled data using a small applied field H (less than or equal to the lower critical field ${\mathit{H}}_{\mathit{c}1}$) parallel and perpendicular to the orthorhombic c axis. A highly anisotropic ${\mathrm{\chi }}_{\mathit{c}}$/${\mathrm{\chi }}_{\mathit{a}\mathit{b}}$ ratio was observed for all three systems, the maximum value of ${\mathrm{\chi }}_{\mathit{c}}$/${\mathrm{\chi }}_{\mathit{a}\mathit{b}}$=9.8 at 5 K and 10.8 at 85 K for the 2:2:2:3 compound (${\mathrm{Bi}}_{1.85}$ ${\mathrm{Pb}}_{0.15}$)