Growth, Microstructure, and Superconducting Properties of Ce Alloyed YBCO Bulk Single-Grain Superconductors

Abstract A novel preform compaction method based on one new type of divisible mould was employed for fabricating single-grain YBCO bulk superconductor, which can complete the preform demoulding process through opening of the mould, rather than pushing the preform out in the regular mould. Thus it has natural superiority on eliminating macro-cracks, which has been proved by the sample surface morphology and the trapped field characterization. In addition, the divisible mould pressed sample exhibits higher levitation force and trapped field properties than the regular mould pressed samples, verifying the potentials of the divisible mould on improving the bulk performance. The optical micrograph results prove the superiority of the divisible mould on eliminating tiny cracks on sample surface. The processing facility and sample reliability brought by the divisible mould should also be emphasized, because the crushing and re-pressing of preform when it presents visible cracks can be omitted and the failed samples with surface cracks will no longer appear. Consequently, the experimental efficiency and stability are both enhanced.

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YBCO Bulk Superconductors with Sm Addition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.891.483 ◽

2017 ◽

Vol 891 ◽

pp. 483-488 ◽

Cited By ~ 2

Author(s):

Daniela Volochová ◽

Vitaliy Antal ◽

Jozef Kováč ◽

Pavel Diko

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Superconducting Properties ◽

Ybco Bulk ◽

Pinning Centers ◽

Bulk Superconductors ◽

Powder Addition ◽

Current Densities ◽

Precursor Powders

The influence of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Precursor powders YBa2Cu3O7-δ (Y-123), Y2O3 and CeO2 were enriched with different amounts of SmBa2Cu3Oy (Sm-123) or Sm2O3 powders with the aim to increase critical current density, Jc,by introducing additional pinning centers. YBCO bulk superconductors with SmBa2Cu3Oy (Y123-Sm) or Sm2O3 (Y123-SmO) powder addition were prepared by the optimized top seeded melt growth process in the form of single grains. Microstructure analysis revealed that Sm2O3 addition leads to a higher amount of smaller Y2BaCuO5 (Y-211) particles, what is related to high critical current densities (Jc ~ 7 x 104 A/cm2) of the YBCO samples with Sm2O3 addition in low magnetic fields. The effect of Sm addition in the form of SmBa2Cu3Oy as well as Sm2O3 powder on Y2BaCuO5 particle size, critical temperature, Tc, and critical current density, Jc, is reported.

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Influence of annealing in oxygen and argon on the superconducting properties of Li-doped YBCO single-grain bulks

Physica C Superconductivity ◽

10.1016/j.physc.2017.08.003 ◽

2017 ◽

Vol 541 ◽

pp. 22-29 ◽

Cited By ~ 5

Author(s):

V. Antal ◽

D. Volochová ◽

V. Kavečanský ◽

J. Kováč ◽

P. Diko

Keyword(s):

Superconducting Properties ◽

Single Grain ◽

Grain Bulks

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Change of Superconducting Properties of Single-Grain Sm–Ba–Cu–O Bulk by Sm/Ba Substitution Effect

IEEE Transactions on Applied Superconductivity ◽

10.1109/tasc.2018.2800770 ◽

2018 ◽

Vol 28 (4) ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Petra Hajdova ◽

Michal Rajnak ◽

Vitaliy Antal ◽

Liudmila Vojtkova ◽

Pavel Diko

Keyword(s):

Substitution Effect ◽

Superconducting Properties ◽

Single Grain ◽

Ba Substitution

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Elimination of Oxygenation Cracking in YBCO Bulk Superconductors

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.409.216 ◽

2009 ◽

Vol 409 ◽

pp. 216-222

Author(s):

Pavel Diko ◽

Xavier Chaud ◽

Vitaliy Antal ◽

Mária Kaňuchová ◽

Martina Šefčíková ◽

...

Keyword(s):

Lattice Parameters ◽

Oxygen Stoichiometry ◽

Low Oxygen ◽

Ybco Bulk ◽

Oxygen Penetration ◽

Thermal Expansion Coefficients ◽

Bulk Superconductors ◽

Single Grain ◽

Expansion Coefficients ◽

Crystal Lattice Parameters

The reasons for cracking of YBa2Cu3Oδ/Y2BaCuO5 (Y123/Y211 or YBCO) bulk single-grain superconductors are mechanical stresses, which arise in the sample during its fabrication. Two main sources of stresses appearing during fabrication were identified: the different thermal expansion coefficients of 123 and 211 phases and the dependence of 123 phase lattice parameters on the oxygen stoichiometry. As-grown YBCO bulks have low oxygen content, YBa2Cu3O6.3, are not superconducting, and must be oxygenated to form YBa2Cu3O7. During standard oxygenation at 400 °C the shortening of crystal lattice parameters causes intensive cracking. The created cracks allow oxygen penetration into the bulk and cause the oxygenation time to be technologically acceptable but reduce significantly the superconducting properties. Here we show that it is possible to eliminate the formation of oxygenation cracks and to reach a critical current density 2.5 times higher than in material bulk oxygenated in a standard way. The oxygenated crack-free samples were obtained by high pressure oxygenation with progressively increasing oxygen partial pressure.

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