Effect of ZrO₂doping on structure and superconducting properties of sintered DyBaCuO ceramics

Abstract

The effect of ZrO 2 addition (1 wt% and 5 wt%) on the superconducting properties of sintered DyBa 2 Cu 3 O y ceramics was studied. The doping was found to assist the formation of secondary phase inclusions such as Dy 2 BaCuO 5 (211), BaZrO 3 and CuO. No traces of Zr in the 123 grains (matrix) were revealed. Doping by ZrO 2 favoured the formation of a fine-grain microstructure, the amount of clean boundaries strongly increasing compared with the undoped composition. Doping by 1 wt% ZrO 2 resulted in a substantial increase in the critical current density J c . The samples with the addition of 5 wt% ZrO 2 showed the best flux pinning in a magnetic field. Such behaviour seems to be associated with a substantial increase in proportion of clean boundaries and the presence of fine facets and regularly distributed dislocations in these boundaries in the doped samples. The measured dependence of the critical current I c on temperature close to T c indicated that weak links at grain boundaries behave as a network of superconductor-insulator-superconductor (SIS) junctions in all compositions, except for the composition with 1 wt% ZrO 2 which showed superconductor-normal metal-superconductor (SNS) behaviour.

Effect of nanoscopic ZrO2particles on flux pinning in (Nd, Eu, Gd)-123/Gd-211 composites

“…EPMA line scanning analysis could not reveal any trace of Zr, either. The sensitivity of EPMA may not be high enough to identify ZrO 2 content less than 1 wt% [10,13]. In addition, the particle size (≈30 nm) was too small for EPMA analyses.…”

Effect of Ca doping on microstructural and superconducting properties of DyBa2Cu3O7 /Caz(0 z 0.2) ceramics

“…The character of the weak-link network was found in a first approximation from I c (T ) dependence as discussed in [17][18][19]. It turned out that Ca doping with z 0.1 leads to a change in the weak-link network character from superconductorinsulator-superconductor (SIS) to superconductor-normalmetal-superconductor (SNS) type (figure 4).…”

“…This discrepancy with our data can be explained by the difference between the ceramic processing in both cases. It is interesting to note that Ca was the only element among several studied doping elements such as Ag, Pt and Zr [17][18][19], which had some finite solubility in '211' inclusions in the sintered doped 123 ceramics.…”

Distinct effects of Al3+ substitution at Cu-site and Al2O3 addition on step-like elastic anomalies and electron–phonon coupling constant in EuBa2Cu3O7−δ superconductors

“…Previous reports of addition of nanosize SnO 2 , ZrO 2 and Al 2 O 3 in bulk superconductors showed such additions enhanced critical current densities and increase flux pinning abilities of the samples [26][27][28][29][30][31][32]. Knowledge on effects of the secondary phase additions on elastic properties of superconductors is also equally important especially for wider practical application of the materials.…”