Texture development of HTS powder-in-tube conductors

Abstract

An overview of the fabrication and electromagnetic properties of high-temperature conductors processed by the powder-in-tube (PIT) technique with reference to texture development and critical anisotropy data is presented. Special emphasis is given to the optimization of the physicochemical and electromagnetic parameters of the multifilamentary and single-filament conductors with superconducting cores of Bi-2223, Tl-1223 and Y-123 superconducting phases. The influence of the multifilamentary and single-filament structures on texture development is discussed. Also, the importance of the local disturbances of the grain alignment and microdefects for the current distribution across and in the plane of the whole conductor is analysed. A comparative study of the critical current anisotropy with field direction in low magnetic fields of Tl-1223 and Bi-2223 conductors manufactured by the PIT technique is presented. For Tl-1223 PIT conductors the anisotropy coefficient shows a very pronounced minimum, followed by a monotonic reduction of anisotropy with the increase of the magnetic field. This is explained in terms of poor grain alignment with weak intergranular superconducting coupling which cause 3D current percolation and also by the demagnetizing effect of the grains and the ceramic core in the PIT Tl-1223 tapes.

Heating rate effect on the evolution of texture in (Bi,Pb)2Sr2Ca2Cu3O10Ag-sheathed tapes

“…At the sheath-ceramic interface, the difference in surface diffusion coefficients of the metallic silver and the oxide ceramic appears to play a significant role in the development of a strong interfacial texture, the high mobility of the Ag atoms promoting the mobility of the atoms constituting the ceramic [5]. The thickness of this textured layer is however limited to a few micrometres [6][7][8].…”

Preparation of Bi2Sr2CaCu2O8-xtracks and thick films by jet printing

“…Several studies on the incongruent melting of the 2212 phase have observed the following solid phases to have formed: 2212, CuO, Bi 3 Sr 4 Ca 3 O x , Sr 1−x Ca x CuO 2 , (Sr 1−x Ca x ) 2 CuO 3 , (Sr 1−x ) 14 Cu 24 O 41 , 2201 [3,[7][8][9]. The composition and type of phases formed is varied and depends upon several factors, including the composition of the starting material, the temperature to which the sample is heated, the atmosphere and the quench rate from the partial melt.…”

“…The role of silver in the development of texture in Bi base layers is related to atomic surface diffusion or the wetting of the silver substrate by the liquid phase formed on melting. The c-axis texturing at the silver superconductor interface is due to the difference of the surface diffusion coefficients, D s , of the silver and oxide ceramic, which cause the silver atoms at the silver-ceramic interface to promote the mobility of the ceramic atoms, apparently reducing binding energy of the ceramic [13,14].…”

(RE)Ba2Cu3O7 Coated Conductors for AC and DC Applications

“…The successful thermal procedure is: 100°C/h 1085°C 0.4h fast cooling to 1035°C cooling 2°C/h 980°C cooling 3°C/h 930°C 60°C/h 420°C 72h 200°C/h RT. [159] on highly textured silver ribbons with a single component {110}<011>, FWHM smaller than 6° in comparison with CVD deposition on highly polished polycrystalline substrates [161] prove the point that smoothness of the substrate has a decisive role in high texture alignment of YBa 2 Cu 3 O 7 on silver not actual texture of the silver [160]. Similar comparative dependence was observed in the case of Tl1223 coatings [162].…”

“…Thus, with increasing magnetic field, the grain size was reduced, but the grain connectivity was improved. Smoothness but not an actual texture of the silver-based substrate has a decisive role in nucleation of the preferentially align HTS coating [160]. The YBa 2 Cu 3 O 7 growth-mode change from the spiral growth mode at zero field to the two-dimensional or three dimensional island growth mode under an external magnetic field which is responsible for improvement of transport property of superconducting coatings [161], Fig.59.…”