Effect of mixing three rare-earth elements on the superconducting properties of

Abstract

We report the effect of mixing three rare-earth (RE) elements in the RE site on the superconducting properties of melt-processed REBa 2 Cu 3 O y , in which RE elements are selected from the group of Nd, Sm, Eu and Gd. The heat treatment profiles for melt processing were determined according to the peritectic decomposition temperatures obtained from the thermal analysis measurements. Microstructural observations and compositional analysis showed that the main phase was (R1 0.33 R2 0.33 R3 0.33 )Ba 2 Cu 3 O y , in which the ratio of three RE elements (R1, R2, R3) was equal to that of the nominal composition, indicating that mixing of RE elements was uniform. All the samples showed relatively high T c in the range 93.1-95.3 K and exhibited the secondary peak effect in the magnetization curves at 77 K with the irreversibility field higher than that of melt-processed Y-Ba-Cu-O. A high J c value of 50 000 A cm −2 at 77 K and 2 T was achieved in (Nd, Eu, Gd)Ba 2 Cu 3 O y for field parallel to the c-axis.

Flux-pinning-induced stress and strain in superconductors: Case of a long circular cylinder

“…1 A record high critical current density of 6ϫ10 4 A/cm 2 at 77 K and a field of 3 T was recently reported for the ternery compound ͑Nd,Eu,Gd͒Ba 2 Cu 3 O y ͑NEG͒ with Pt additions. 2 By these improvements the potential has grown considerably for the use of HTS single-domain bulks in a number of applications such as trapped-field magnets and levitating bearings, and one sees today an intensive activity in this direction. 3 Because the mere size of the HTS is a crucial parameter the magnetic characterization of these materials is often made by recording maps of the field distribution trapped by a full-sized sample.…”

Flux pinning in ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy melt-processed superconductors

“…7 Finally, a sample is cut to dimensions aϫbϫc ϭ2.6ϫ1.7ϫ1 mm 3 . The crystallization process was initialized by a MgO ͗100͘ seed which was placed at the center on top of the basal pellet surface.…”

Field-Cooled Flux Distributions as Tool to Analyze Pinning Properties

“…Details of the sample preparation can be found elsewhere. 15) Samples were cut so that the c-axis is oriented perpendicular to the sample surface. All samples were mechanically polished down to 1 µm roughness which ensures a good reflectivity and uniform images.…”