Hiroshi Maeda

Superconducting properties of single-crystal whiskers of (Y0.86Ca0.14)Ba2Cu3Ox grown from precursors containing calcium and tellurium

Single-crystal whiskers of YBa2Cu3Ox (Y-123) phase with a length of about 2.5 mm were grown from sintered precursor powders with a nominal composition of Y1Ba2Cu3Te0.5Ca1.0Ox. Electron probe microanalysis analyses showed that the whiskers contain Ca but no Te with a composition of (Y0.86Ca0.14)Ba2Cu3Ox in which 14%Y is substituted by Ca. The precursor powder is composed of Ca-doped Y-123 and (BaCa)3TeO6 phases. The presence of the (BaCa)3TeO6 plays an important role in enhancing the growth of the whiskers. The whiskers show a critical temperature Tc of about 83 K and a critical current density, Jc of 4.4×104u2009A/cm2 at 82 K and self-field along the c axis. The whiskers exhibit interesting intrinsic Josephson effects along the c axis.

Effect of magnetic field strength in melt-processing on texture development and critical current density of Bi-oxide superconductors

Abstract Vertical magnetic fields up to 15 T were applied to the magnetic melt-processing (MMP) of Bi2212 bulks and Ag-sheathed tapes with a core thickness above 80 μm, which were set horizontally. Texture with the c -axis along the direction of magnetic field applied during MMP is developed due to the anisotropy in magnetic susceptibility of Bi2212. The degree of texture and the anisotropy factor in magnetization increase almost linearly as the magnetic field strength H a during MMP is increased. The anisotropy factor in magnetization reaches 6.5 at a H a of 13 T for Ag-doped Bi2212 bulks, whereas for Bi(Pb)2212 in which Pb partially substitutes for Bi the factor is suppressed to a half of that of Ag-doped Bi2212. The transport critical current I c and the critical current density J c of Bi2212 tapes also increase with increasing H a due to the texture development and I c reaches above 1000 A in self-filed for the tapes with a core thickness of 180 μm. However, for further thicker tapes, I c decreases. The suppressions in the I c for the tapes and in the anisotropy factor in magnetization for Bi(Pb)2212 bulks are due to inhomogeneous melting, and inhomogeneous nucleation and growth of crystals during MMP. When crystal growth is restricted, crystal alignment is suppressed.

Growth of R-123 Phase Single Crystal Whiskers

Single-crystal whiskers of R1Ba2Cu3Ox (R-123, R = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu) phase have been successfully grown by the Te- and Ca-doping method. The whiskers were grown from precursor pellets at just below their partial melting (peritectic) temperatures. The nominal composition of the R-123 whiskers is R1+uBa2+vCawCu3Ox (u+v+w=0, w>0) with R and/or Ba sites being substituted by Ca. However, the amount of Te was less than the analytical limit. The critical temperatures of the R-123 whiskers were around 80 K, and among these whiskers those with larger R ionic radii such as Dy, Gd, Eu and Sm require post-annealing in an oxygen atmosphere.

Periodic oscillations of Josephson-vortex flow resistance in oxygen-deficient Y Ba 2 Cu 3 O x

We measured the Josephson vortex flow resistance as a function of magnetic field applied parallel to the

Intrinsic Josephson junctions in Y1Ba2Cu3Ox single-crystal whiskers grown using Te-doped precursors

ab

Critical current density and microstructures of thick monocore Bi2212 tapes grown in high magnetic fields

planes using annealed

Growth and Anisotropic Properties of RBa2Cu3Ox Single-Crystal Whiskers

mathrm{Y}{mathrm{Ba}}_{2}{mathrm{Cu}}_{3}{mathrm{O}}_{x}

Phase Formation and Critical Current Density of Ag‐Sheathed Bi‐2223 Tapes with Insulating Sr‐V‐O Barriers

intrinsic Josephson junctions having high anisotropy

Growth and superconducting properties of Y-123 phase single-crystal whiskers using Te and Ca doped precursors

(ensuremath{sim}40)

Fabrication and Jc property of Ag-sheathed Bi2223 multifilamentary tapes with Sr-V-O barriers

by oxygen content reduction. Periodic oscillations were observed in magnetic fields above