Employment of NdBCO/YBCO/MgO film seed in the infiltration growth technique for fabricating single-grain YBCO bulk superconductors

Single grain YBCO bulk superconductors were prepared from different starting precursors. In the first case, Y2Ba1Cu1O5 (Y211) powder as the solid phase and the liquid phase of mixture of YBa2Cu3O7-x+BaCuO2+CuO powders were used. In the second case the solid phase was prepared from the mixture of Y2O3+BaCuO2 instead of the conventionally used Y211. The microstructure of samples was studied by polarized light microscopy and scanning electron microscope (SEM). The influence of different staring compositions on the final size of Y211 particles is shown. Also the influence of BaCuO2 concentration in the Y2O3+x·BaCuO2 (x=0.2; 0.5; 0.8; 1; 1.2; 1.5; 1.8) mixture on the Y211 size was studied.

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Influence of preforming pressure on the morphology and properties of single-grain Y–Ba–Cu–O superconductors by the 011-type infiltration growth technique

Materials Today Communications ◽

10.1016/j.mtcomm.2021.102771 ◽

2021 ◽

pp. 102771

Author(s):

Guo-Zheng Li ◽

Miao Wang

Keyword(s):

Growth Technique ◽

Single Grain ◽

Infiltration Growth

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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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