T. Frello

Structural studies of BSCCO/Ag-tapes by high-energy synchrotron X-ray diffraction

Abstract High-energy (100 keV) synchrotron X-ray diffraction has been identified as a powerful tool for characterizing texture and structural phases within Ag clad high T c superconducting tapes of the (Bi,Pb)–Sr–Ca–Cu–O (BSSCO) type during synthesis of (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x (Bi-2223) from (Bi,Pb) 2 Sr 2 CaCu 2 O x (Bi-2212). Using a CCD camera, the texture and concentration of the dominant structural phases can be determined simultaneously within fractions of minutes. As an example, we report on the in situ annealing behavior in air at 835°C of an as-rolled monofilament tape. It is shown that the alignment of the superconducting grains takes place almost exclusively in the Bi-2212 phase. During heating, the texture profile narrows rapidly above 750°C, coincident with the dissolution of (Ca,Sr) 2 PbO 4 . A 98% conversion of Bi-2212 is obtained within 19 h, but furnace cooling leads to the formation of secondary phases such as Bi-2201 and (Ca,Sr) 2 PbO 4 . Room temperature data on similar tapes show that subsequent deformation and annealing results in a higher Bi-2223 phase purity while slightly deteriorating the grain alignment.

Oxygen-ordering superstructures in underdoped YBa 2 Cu 3 O 6 + x studied by hard x-ray diffraction

High-energy x-ray diffraction is used to investigate the bulk oxygen-ordering properties of

Superstructure formation and the structural phase diagram of YBa2Cu3O6+x

{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+x}.

In situ study of equilibrium phenomena and kinetics in a BiSCCO/Ag tape

Four different superstructures of Cu-O chains aligned along the b axis and ordered with periodicity

Charge stripes seen with X-rays in La1.45Nd0.4Sr0.15CuO4

ma,

Dynamics of Oxygen ordering in YBa2Cu3O6+x studied by neutron and high-energy synchrotron x-ray diffraction

along the a axis have been observed. For

Cooling behavior of BSCCO/Ag tapes

xl0.62,

Instability of the critical state in NdBa2Cu3O7-δ single crystals

the only observed superstructure is ortho-II with

Instability of the critical state in NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystals

m=2.

Detailed Study of Charged Stripes in La1.6−xNd0.4SrxCuO4

At room temperature, we find ortho-III