Disordering effects in the atomic structure of fine-crystalline HTSC YBa{sub 2}Cu{sub 3}O{sub y}

• Published in: Journal of experimental and theoretical physics 2012-06, Vol.114 (6)
• Main Authors: Balagurov, A. M., Mamsurova, L. G., Bobrikov, I. A., Loan, To Thanh, Pomjakushin, V. Yu, Pigalskiy, K. S., Trusevich, N. G., Vishnev, A. A.
• Format: Article
• Language: English
• Subjects: BARIUM COMPOUNDS; CATIONS; COHERENCE LENGTH; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; CUPRATES; HIGH-TC SUPERCONDUCTORS; LAYERS; MAGNETIC FIELDS; MAGNETIZATION; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; NEUTRON DIFFRACTION; OXYGEN; PENETRATION DEPTH; PROBABILITY; SUPERCONDUCTIVITY; SYNTHESIS; TRANSITION TEMPERATURE; YTTRIUM COMPOUNDS
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S106377611204005X

The atomic structure of YBa{sub 2}Cu{sub 3}O{sub y} fine-crystalline HTSC samples with various average crystallite sizes Left-Pointing-Angle-Bracket D Right-Pointing-Angle-Bracket ranging from 0.4 to 2 {mu}m and an oxygen concentration y close to the optimal value for superconductivity (y Almost-Equal-To 6.93) is investigated by the neutron diffraction technique. We have found some effects associated with the redistribution of cations and oxygen atoms and with variations in the positions of atomic layers in the unit cell, which are not observed in macrocrystalline samples. In all probability, these effects appear due to nonequilibrium conditions of synthesis required for obtaining this compound in the fine-crystalline state. The results have made it possible to explain the peculiar physical properties of fine-crystalline YBa{sub 2}Cu{sub 3}O{sub y} samples (in particular, the coexistence of high superconducting transition temperatures T{sub c} and noticeably lower values of magnetization in strong magnetic fields for T < T{sub c}). It is shown that a nanoscale structural inhomogeneity exists in fine-crystalline YBa{sub 2}Cu{sub 3}O{sub y} samples with the optimal oxygen content and changes the fundamental superconducting parameters, viz., the magnetic field penetration depth and the coherence length.