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Journal articles on the topic 'YBa2Cu3O7'

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Published: 4 June 2021

Last updated: 3 February 2022

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1

Zhou, Zhigang, and Alexandra Navrotsky. "Thermochemistry of the Y2O3–BaO–Cu–O system." Journal of Materials Research 7, no. 11 (1992): 2920–35. http://dx.doi.org/10.1557/jmr.1992.2920.

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High temperature reaction calorimetry using molten lead borate as a solvent is used to study the thermochemistry of phases in the Y2O3–BaO–Cu–O system. Enthalpies of formation of YBa2Cu3Ox (6 < x < 7), YBa2Cu4O8, Y2BaCuO5, Y2Cu2O5, and BaCuO2.01 phases have been determined. The thermodynamic relationships among these phases at room temperature have been assessed. The results show that the 123 phase is not thermodynamically stable with respect to assemblages containing combinations of Y2BaCuO5, Y2Cu2O5, BaCuO2, Y2O3, and CuO. The fully oxidized 123 phase is not stable with respect to the 124 and the above assemblages. Reactions at room temperature are shown as follows: YBa2Cu3O7 (s) + CuO (s) → YBa2Cu4O8 (s); δH = −31.9 ± 22.3 kJ mol−1 and YBa2Cu3O6.76 (s) → ½YBa2Cu4O8 (s) + ¼Y2BaCuO5 (s) + ¾BaCuO2.01 (s); δH = −78.9 ± 21.0 kJ mol−1.

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2

Milonopoulou, V., K. M. Forster, J. P. Formica, J. Kulik, J. T. Richardson, and D. Luss. "Influence of oxygen partial pressure on the kinetics of YBa2Cu3O7−x formation." Journal of Materials Research 9, no. 2 (1994): 275–85. http://dx.doi.org/10.1557/jmr.1994.0275.

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The YBa2Cu3O7−x formation kinetics from a spray-roasted precursor powder containing Y2O3, BaCO3, and CuO was followed via in situ, time-resolved x-ray diffraction as a function of gas atmosphere and temperature. In inert atmospheres, BaCO3 and CuO form BaCu2O2 which subsequently reacts with Y2O3 to form YBa2Cu3O6. However, YBa2Cu3O6 decomposes at temperatures exceeding 725 °C with Y2BaCuO5 being one of the decomposition products. In oxidizing atmospheres, YBa2Cu3O7−x formation involves the BaCuO2. At high temperatures (800–840 °C), oxygen increases the yield of YBa2Cu3O6. A nuclei growth model assuming two-dimensional, diffusion-controlled growth with second-order nucleation rate fits the experimental data.

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3

Garzon, Fernando H., Ian D. Raistrick, D. S. Ginley, and John W. Halloran. "Thermodynamic instability of the YBa2Cu3O7−x phase at the 1:2:3 composition." Journal of Materials Research 6, no. 5 (1991): 885–87. http://dx.doi.org/10.1557/jmr.1991.0885.

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We have measured enthalpies of formation of YBa2Cu3O7−x, Y2BaCuO5, YBa2Cu4O8, and BaCuO2 using high precision isothermal solution calorimetry. Thermodynamic analysis of the calorimetric data indicates that YBa2Cu3O7−x at the pure-phase composition (1:2:3 cation ratio) is metastable at ≍873 K and 1 atm Po2.

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4

Cargnoni, Fausto, and Marco Scavini. "Direct-space analysis of the electronic structure of the YBa2Cu3O6 and YBa2Cu3O7 crystals." Canadian Journal of Chemistry 80, no. 3 (2002): 235–44. http://dx.doi.org/10.1139/v02-014.

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The electronic structure of the YBa2Cu3O6 and YBa2Cu3O7 crystals is investigated by means of fully periodic-restricted HartreeFock LCAO (linear combination of atomic orbitals) pseudopotential calculations. To give a detailed description of the bonding and atomic properties of the materials studied we selected the quantum theory of atoms in molecules approach, and complementary information is obtained from the analysis of the electron localization function in specific cell regions. The main features of the YBa2Cu3O6 and YBa2Cu3O7 crystals' electron densities are detailed and compared with available experimental data. Since the superconducting transition requires oxidation of the YBa2Cu3O6 crystal, we focused on the electronic rearrangements related to the inclusion of oxygen. CuO planes, probably responsible for the superconducting transition, exhibit peculiar electronic properties.Key words: superconducting cuprates, electron density, ab initio calculations.

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5

Brinkmann, Detlef, and Andrei Yu Zavidonov. "Nuclear Spin-lattice Relaxation in Cuprate Superconductors – Some New Approaches." Zeitschrift für Naturforschung A 57, no. 6-7 (2002): 479–87. http://dx.doi.org/10.1515/zna-2002-6-735.

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This paper reviews theoretical studies of nuclear spin-lattice relaxation we have made for the normal state of the cuprate high-temperature superconductors YBa2Cu3O7, YBa2Cu4O8, and La2-xSrx CuO4. In the case of planar sites, we calculated the dynamic spin susceptibility within a constraint-free theory based on the presentation of the model in terms of Hubbard operators. The results for 63Cu, 17O, and 89Y are in good agreement with experimental data. The relaxation (and the Knight shift) of chain Cu in YBa2Cu3O7 and YBa2Cu4O8 requires a different treatment; our approach uses the Luttinger-liquid model. Again, good agreement with experiment is achieved

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6

Della Valle, Raffaele Guido. "Lattice stability of YBa2Cu3O6 and YBa2Cu3O7." Physica C: Superconductivity 185-189 (December 1991): 1679–80. http://dx.doi.org/10.1016/0921-4534(91)90966-3.

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7

Owens, F. J., B. L. Ramakrishna та Z. Iqbal. "EPR in YBa2Cu3O7−δ and YBa2Cu3O6+x". Physica C: Superconductivity 156, № 2 (1988): 221–24. http://dx.doi.org/10.1016/0921-4534(88)90811-8.

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8

Watanabe, H., B. Kabius, B. Roas, and K. Urban. "Xenon ion irradiation of superconducting YBa2Cu3O7 thin films." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (1990): 92–93. http://dx.doi.org/10.1017/s0424820100173595.

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Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

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9

Huong, Pham V. "Microstructure of superconductor bulk materials and thin films." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (1992): 1542–43. http://dx.doi.org/10.1017/s0424820100132340.

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The microstructure of single crystals of Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O prepared by different methods were studied by various physical techniques, in particular by Raman microspectroscopy.Correlations have been established between Raman spectra and structure, allowing the determination of crystalline geometry of the material versus the composition and the preparation parameters.For YBa2Cu3Ox, a relationship: x = 0.025 VH - 5.57 is proposed and permits to evaluate the oxygen content by measuring simply in ZZ scattering geometry the Cu-O stretching mode V'H along the c axis of the crystal. This frequency varies from 465 cm-1 in YBa2Cu3O6 to 503 cm-l in YBa2Cu3O7 (Fig.l).This technique also offers the possibility to follow the structural conversion Y124 into Y123 and TI2212 into TI1212 (Fig.2) by appropriate thermal treatment. The preferentiel departure of the “CuO” or “TIO” chain/layer (Fig.3) is explained by weaker interaction forces between these layers and the adjacent ones, compared to those between the remaining layers. This helps to predict the localization of an eventual intercation in Y123 and TI1212.

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10

HANUZA, J., J. KLAMUT, R. HORYŃ, and B. JEŹOWSKA-TRZEBIATOWSKA. "THE POSSIBILITY OF THE LIBRATIONAL MECHANISM OF HIGH-TEMPERATURE SUPERCONDUCTIVITY IN THE YBa2Cu3O7−x TYPE TERNARY OXIDE." Modern Physics Letters B 02, no. 03n04 (1988): 667–71. http://dx.doi.org/10.1142/s0217984988000321.

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IR absorption and reflectance spectra as well as Raman scattering spectra of the YBa2Cu3O 7−x superconductor in the orthorhombic phase have been measured at temperatures below and above the critical point. The role of librational modes in the superconductive transition is discussed. The mechanism of the high-temperature superconductivity of YBa2Cu3O7− x is proposed based on the electron coupling by libron.

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11

Ruzieva, M., Q. Bobomurodov, S. Bobomurodov, and R. Shokirov. "PROBLEMS OF COEXISTENCE OF SUPERCONDUCTIVITY AND MAGNETIC ORDERING OF COPPER SUBLATTICES IN YBa2Cu3-XFeXO7-X CERAMICS." Technical science and innovation 1 (May 20, 2020): 57–62. http://dx.doi.org/10.51346/tsai.vl1.2020-0001.

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The article studies the problems of coexistence of superconductivity and magnetic ordering of copper sublattices in YBa2Cu3-xFexO7-x ceramics. It is known that in superconducting ceramics YBa2Cu3O7-z with orthorhombic lattice as the oxygen content decreases, the transition temperature in superconducting state Tc decreases, and at z>0.6 superconductivity disappears, the lattice becomes tetragonal and at the same time, antiferromagnetic ordering of sublattices Cu (2) appears. The substitution in ceramics of YBa2Cu3O7 part of copper atoms by iron atoms (i.e., the formation of a solid solution of YBa2Cu3-xFexO7+y) is accompanied by similar effects: as x increases, Tc decreases, at x>0.05 the orthorhombic lattice becomes tetragonal, at x>0.45 the superconductivity disappears. The most significant moment is the fact of coexistence in ceramics YBa2Cu3-xFexO7+y in the region of compositions 0.03 < x < 0.45 of superconductivity and magnetic ordering of iron atoms in copper nodes (the latter is established by Mossbauer spectroscopy on isotope 57Fe in a large number of works. However, it remains unclear whether the magnetic ordering of iron atoms in the YBa2Cu3-xFexO7+y lattice is related to the magnetic ordering of copper atoms

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12

Tröger, W., та T. Butz. "Oxygen Diffusion in YBa2Cu3O7–δ Studied via 133Ba(EC)133Cs Nuclear Quadrupole Interaction". Zeitschrift für Naturforschung A 47, № 1-2 (1992): 12–20. http://dx.doi.org/10.1515/zna-1992-1-205.

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AbstractThe oxygen diffusion in YBa2Cu3O7-δ was studied between 300 K and 1273 K in flowing oxygen by monitoring the 133Ba(EC)133 Cs nuclear quadrupole interaction by time differential perturbed angular correlation. The data are analyzed in a model of two different nearest neighbour oxygen configurations and yield hopping rates, the energy barrier and the difference in free enthalpy between both states. In addition, we studied the reduced system YBa2Cu3O6 +ε.

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13

Irwin, J. C., J. Chrzanowski, E. Altendorf, J. P. Franck, and J. Jung. "A Raman investigation of isotope exchange in YBa2Cu3O7−x." Journal of Materials Research 5, no. 12 (1990): 2780–89. http://dx.doi.org/10.1557/jmr.1990.2780.

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Raman scattering experiments have been carried out on sintered pellets of YBa2Cu3−16O7−x and YBa2Cu318O7−x. The latter samples were obtained both by gas exchange and by growth with substituted oxides. Three of the observed Raman modes arise from motion of the oxygen atoms only and have nominal frequencies of 500, 435, and 340 cm−1 at room temperature in the 16O compound with x = 0. The frequencies of these modes shift significantly with oxygen isotope exchange, and these frequency shifts have been measured for several sets of samples. The results indicate that in samples prepared primarily by gas exchange the degree of exchange on the O(2) and O(3) planar sites is greater than the degree of exchange on the bridging O(4) site. Linewidth measurements have revealed that the O(4) phonon (500 cm−1) is significantly broadened by 18O exchange, and this is attributed to a random occupation of the O(4) site by 18O and 16O. The results are discussed in the context of recent measurements of oxygen diffusion in YBa2Cu3O7−x and a proposed mode for the oxygen exchange mechanism. Measurements have also been carried out on YBa263Cu316O7−x and YBa265Cu316O7−x. The results confirm that the Raman mode at 150 cm−1 arises from motion of the Cu(2) planar copper atoms.

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14

Sabatini, R. L., Yimei Zhu, Masaki Suenaga, and A. R. Moodenbaugh. "Low-temperature annealing of YBa2Cu3O7-x." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (1992): 88–89. http://dx.doi.org/10.1017/s0424820100120849.

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Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.

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15

Chisholm, M. F. "Grain boundaries in high-Tc superconductors." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 1008–9. http://dx.doi.org/10.1017/s0424820100107101.

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One crucial property for most superconductor applications is the materials critical current density. Measurements on single crystals of YBa2Cu3O7, show critical currents to be in excess of 105 A/cm2 at 77K. However, polycrystalline samples show values of 103 A/cm2 or less at 77K. The critical current, unlike other superconductivity properties, is not a property of a specific composition but of a specific sample. Defects, introduced during the material processing, exert a pinning force which makes it possible for Type-II superconductors to carry current without losses. At the same time these defects represent an interruption in the structural and chemical order which has been shown to be necessary for superconductivity in the YBa2Cu3Ox phase, and so they may also act as a weak link in the conduction path. The most direct measurements of the role of individual grain boundaries on the critical current density are those of Chaudhari et al. who examined patterned YBa2Cu3O7 films grown on SrTiO3 substrates.

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16

Tao, Y. K., J. S. Swinnea, A. Manthiram, J. S. Kim, J. B. Goodenough та H. Steinfink. "Co and Fe substitution in YBa2Cu3O7−δ". Journal of Materials Research 3, № 2 (1988): 248–56. http://dx.doi.org/10.1557/jmr.1988.0248.

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The limiting substitution of Co or Fe for Cu in the orthorhombic superconducting phase YBa2Cu3O7−δ yields the tetragonal, semiconducting compositions YBa2Cu2CoO7.25 and YBa2Cu2.5 Fe0.5O7.19 after annealing at 400°C and slow cooling in O2. Single-crystal x-ray structural analyses, conductivity and magnetic-susceptibility measurements, and thermogravimetric analysis (TGA) data provide evidence for Co or Fe substitution at the Cu (1) position and intercalation of peroxide ions (O2)2− The two compositions decompose for disintercalation of oxygen beyond O6.7 for Co and O6.4 for Fe when heated in N2. The Cu(2) atoms of tetragonal YBa2Cu4O6 appear to be antiferromagnetic below a Tn ∼ 240 K, which is similar to comparable Cu–O planar nets in stoichiometric La2CuO4.

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17

Rauch, W., H. Behner, G. Gieres та ін. "Sputtering of YBa2Cu3O7−δ/NdAlO3/YBa2Cu3O7−δtrilayers". Applied Physics Letters 60, № 26 (1992): 3304–6. http://dx.doi.org/10.1063/1.106674.

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18

Kusz, B., and L. Murawski. "The internal friction in superconducting YBa2Cu3O7 and semiconducting YBa2Cu3O6 ceramics." Solid State Communications 67, no. 4 (1988): 435–37. http://dx.doi.org/10.1016/0038-1098(88)91061-7.

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19

Ramasesha, Sheela K. "Thermoelectric Power of YBa2Cu3O7-Xand YBa2Cu4O8Under Pressure." Active and Passive Electronic Components 15, no. 3-4 (1993): 147–53. http://dx.doi.org/10.1155/1993/32872.

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Thermoelectric power (TEP) of YBa2Cu3O7-X(123) and YBa2Cu4O8(124) samples are measured as a function of pressure. The TEP of an as-sintered 123 polycrystalline sample shows a broad maximum around 1.25 GPa whereas that of the cold-pressed sample decreases steadily. The ab-plane TEP of 123 single crystal decreases monotonically and the c-axis TEP exhibits a maximum around 1.5 GPa. Disappearance of the broad maximum in the polycrystalline sample upon cold-pressing is interpreted in terms of the crystallite orientation occurring under pressure. TEP of the 124 polycrystalline sample decreases sharply up to 4.5 GPa and at a lower rate with further increase in pressure, a trend similar to that is observed in the variation of Tcas a function of pressure.

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20

Zhang, J. P., D. J. Li, C. Boldt, et al. "Microstructure and properties of Cu-rich 123: Part II. Homogeneous copper and high magnetic Jc." Journal of Materials Research 8, no. 6 (1993): 1232–39. http://dx.doi.org/10.1557/jmr.1993.1232.

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Copper- and yttrium-rich YBa2Cu3O7 bulk superconductors have been prepared by mixing copper oxide or yttrium oxide in nitric acid and adding the solution to premade stoichiometric YBa2Cu3O7 followed by annealing. In contrast to materials made by mixing oxide powders, both samples contain copper-rich defects spread homogeneously throughout the grains, either small platelet copper oxide precipitates or bundles of planar defects (Cu–O double planes). These materials also show large magnetic hysteresis at 77 K, comparable to the results obtained from decomposed YBa2Cu4O8. This implies that small copper oxide precipitates and bundles of planar defects are strong flux pinners, and indicates a processing route to producing large amounts of strongly intragranular pinned superconductors. However, the materials also show clean grain boundaries, so an equally valid interpretation is that there is a substantial component of intergranular superconductivity in field, enhancing the effective circuit size to a value far larger than the grain size.

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21

Prieto, P., D. Araujo, M. Chacon, M. E. Gomez, L. F. Castro, and E. Solarte. "Superconducting properties of epitaxial YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 heterostructures." Physica C: Superconductivity 185-189 (December 1991): 2029–30. http://dx.doi.org/10.1016/0921-4534(91)91139-u.

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22

Gijs, M. A. M., J. B. Giesbers, F. C. M. J. M. van Delft, C. E. Timmering, A. M. Gerrits та A. Slob. "Submicron YBa2Cu3O7−δ‐Ag‐YBa2Cu3O7−δsuperconducting proximity junctions". Applied Physics Letters 59, № 10 (1991): 1233–35. http://dx.doi.org/10.1063/1.105513.

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23

Putzke, Carsten, Liam Malone, Sven Badoux, et al. "Inverse correlation between quasiparticle mass and Tc in a cuprate high-Tc superconductor." Science Advances 2, no. 3 (2016): e1501657. http://dx.doi.org/10.1126/sciadv.1501657.

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Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature Tc is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-Tc superconductivity. We have tested the robustness of this correlation between m* and Tc by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as Tc increases under pressure. This inverse correlation between m* and Tc suggests that quantum fluctuations of the charge order enhance m* but do not enhance Tc.

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24

Wen, J. G., S. Mahajan, H. Ohtsuka, T. Morishita та N. Koshizuka. "Study of the growth mechanism of highly in-plane aligned α-axis YBa2Cu3O7−x thin films on LaSrGaO4 substrate by high resolution electron microscopy". Journal of Materials Research 11, № 12 (1996): 2951–54. http://dx.doi.org/10.1557/jmr.1996.0372.

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Highly in-plane aligned α-axis YBa2Cu3O7−x thin films deposited on (100) LaSrGaO4 substrates by a self-template method were studied by high-resolution electron microscopy along three orthogonal 〈100〉 axes of the substrate. Plan-view images confirm that the majority of the film preferentially aligns across the entire substrate except for very few misaligned domains with average size 10 nm2. Cross-sectional images along the [100] orientation of YBa2Cu3O7−x reveal that in-plane aligned α-axis YBa2Cu3O7−x is grown on a template layer dominated by c-axis oriented film. This strongly suggests that the in-plane alignment of α-axis YBa2Cu3O7−x thin films on (100) LaSrGaO4 substrates is governed by the different stresses along the b and c axes of the substrate. Cross-sectional images along [001] of the YBa2Cu3O7—x thin film reveal that the 90° domains easily nucleate in the region between α-axis YBa2Cu3O7—x and the YBa4Cu3Ox phase. Cracks along the (001) plane of YBa2Cu3O7−x are found to be due to the large mismatch between the c parameters of the thin film and substrate.

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25

Wu, Chuanbao, and Yunwei Wang. "Enhancement of Critical Current Density by Establishing a YBa2Cu3O7−x/LaAlO3/YBa2Cu3O7−x Quasi-Trilayer Architecture Using the Sol-Gel Method." Coatings 9, no. 7 (2019): 437. http://dx.doi.org/10.3390/coatings9070437.

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We developed a solution-derived method to establish a YBa2Cu3O7−x/LaAlO3/YBa2Cu3O7−x quasi-trilayer architecture. Using the method, nano-scale pinning sites were induced into the quasi-trilayer architecture and yielded an apparent improvement in the in-field critical current density (Jc) of high-quality YBa2Cu3O7−x (YBCO). The improvement in the in-field Jc of the films was closely related to the thickness of the LaAlO3 (LAO) interlayer. In this paper it is demonstrated that when the nominal interlayer thickness approximates 20 nm, which is slightly higher than the roughness of the YBa2Cu3O7−x surface, the LaAlO3 interlayer is discontinuous due to synchromesh-like growth of the LaAlO3 layer on relatively rough YBa2Cu3O7−x surface resulting from the mobility of the solution. Nanoscale defects, such as particles, some amorphous phases, and especially their concomitant lattice defects (such as stacking faults and plane buckling) arise in YBa2Cu3O7−x layers. These nanoscale defects could play a role in flux pinning and thus enhancing Jc. The effective non-vacuum solution to induce vortex pinning into YBa2Cu3O7−x films could be a reference for the further design of an optimal pinning landscape for higher Jc.

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26

Sahling, A., and S. Sahling. "Glassy behavior of low-temperature energy relaxation in YBa2Cu3O7 and YBa2Cu3O6." Journal of Low Temperature Physics 77, no. 5-6 (1989): 399–411. http://dx.doi.org/10.1007/bf00682752.

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27

Nakajima, Minoru, and Masakazu Matsui. "Tem study of YBa2Cu3O7−x/MgO/YBa2Cu3O7−x trilayers." Physica C: Superconductivity 185-189 (December 1991): 2043–44. http://dx.doi.org/10.1016/0921-4534(91)91146-u.

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28

Gausepohl, S. C., Mark Lee, and K. Char. "Supercurrent distributions in YBa2Cu3O7–YBa2Co0.21Cu2.79O7–YBa2Cu3O7 edge Josephson junctions." Applied Physics Letters 68, no. 16 (1996): 2279–81. http://dx.doi.org/10.1063/1.115884.

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29

Char, K., L. Antognazza, and T. H. Geballe. "Properties of YBa2Cu3O7−x/YBa2Cu2.79Co0.21O7−x/YBa2Cu3O7−xedge junctions." Applied Physics Letters 65, no. 7 (1994): 904–6. http://dx.doi.org/10.1063/1.112196.

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30

Jackson, E. M., B. D. Weaver, and G. P. Summers. "Proton damage effects in YBa2Cu3O7/YBa2Cu2.79Co0.21O7/YBa2Cu3O7 Josephson junctions." Applied Physics Letters 71, no. 2 (1997): 273–75. http://dx.doi.org/10.1063/1.119517.

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31

Wang, S. Z., E. Olsson, J. A. Alarco, et al. "YBa2Cu3O7/NdGaO3/YBa2Cu3O7 trilayers by modified off‐axis sputtering." Journal of Applied Physics 73, no. 11 (1993): 7543–48. http://dx.doi.org/10.1063/1.354002.

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32

Sakai, Joe, Jun-ichi Hioki, Takaaki Ohnishi, Toru Yamaguchi, and Syozo Imai. "YBa2Cu3O7-z/Pr0.5Ca0.5MnO3-y/YBa2Cu3O7-zSandwich Type Josephson Junctions." Japanese Journal of Applied Physics 37, Part 1, No. 6A (1998): 3286–89. http://dx.doi.org/10.1143/jjap.37.3286.

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33

Niemeyer, J., N. D. Kataria, M. R. Dietrich, et al. "Ac-Josephson effect in YBa2Cu3O7/YBa2Cu3O7 point contact junctions." Zeitschrift für Physik B Condensed Matter 69, no. 1 (1987): 1–9. http://dx.doi.org/10.1007/bf01560602.

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34

Yoshida, J., T. Hashimoto, and K. Mizushima. "Anomalous Josephson coupling in YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 trilayer junctions." Physica B: Condensed Matter 194-196 (February 1994): 1657–58. http://dx.doi.org/10.1016/0921-4526(94)91328-5.

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35

Asayama, K., Y. Kitaoka, G. Q. Zheng, et al. "NMR of High-Tc Superconductors." International Journal of Modern Physics B 12, no. 29n31 (1998): 3207–15. http://dx.doi.org/10.1142/s0217979298002337.

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Recent NMR measurements on high-T c materials by our group are reviewed. Study of YBa2Cu3O7+Ni has revealed that the attractive force is spin in origin. Analysis of T1, the Knight shift K and T2G in Tl2Ba2Ca2CuO10 (Tl2223), HgBa2Ca2Cu3O8 (Hg1223), HgBa2Ca3Cu4O10 (Hg1234) and YBa2Cu4O8 (Y1248) supports the antiferromagnetic spin fluctuation (AFSF)-mediated-superconductivity-model. The temperatures at which a pseudogap starts to open obtained by 1/T1T, dK/dT, photoemission, resistivity and STM all agree with each other in Bi2Sr2CaCu2O8 (Bi2212). The origin of the pseudogap is discussed.

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36

Jose, R., Asha M. John, J. Kurian, P. K. Sajith та J. Koshy. "REBa2ZrO5.5 (RE = La, Ce, Eu, and Yb): Synthesis, characterization, and their potential use as substrates for YBa2Cu3O7–δ superconductors". Journal of Materials Research 12, № 11 (1997): 2976–80. http://dx.doi.org/10.1557/jmr.1997.0392.

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A new class of complex perovskites REBa2ZrO5.5 (where RE = La, Ce, Eu, and Yb) have been synthesized and sintered as single phase materials by the solid state reaction method. The structure of these materials was studied by x-ray diffraction, and all of them were found to be isostructural, having a cubic perovskite structure. X-ray diffraction and resistivity measurements have shown that there is no detectable chemical reaction between YBa2Cu3O7–delta; and REBa2ZrO5.5 even under severe heat treatment at 950 °C, and that the addition of REBa2ZrO5.5 up to 20 vol.% in YBa2Cu3O7–δ shows no detrimental effect on the superconducting properties of YBa2Cu3O7-δ. Dielectric constants and loss factors are in the range suitable for their use as substrates for microwave applications. Thick films of YBa2Cu3O7–δ fabricated on polycrystalline REBa2ZrO5.5 substrates gave a zero resistance transition temperature Tc(0) ∼ 92 K, indicating the suitability of these materials as substrates for YBa2Cu3O7–δ.

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37

Eibl, O., G. Gieres, and H. Behner. "Microstructure of YBa2Cu3O7-x thin films deposited by dc sputtering." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 172–73. http://dx.doi.org/10.1017/s0424820100152835.

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The microstructure of high-Tc YBa2Cu3O7-X thin films deposited by DC-sputtering on SrTiO3 substrates was analysed by TEM. Films were either (i) deposited in the amorphous state at substrate temperatures < 450°C and crystallised by a heat treatment at 900°C (process 1) or (ii) deposited at around 740°C in the crystalline state (process 2). Cross sections were prepared for TEM analyses and are especially useful for studying film substrate interdiffusion (fig.1). Films deposited in process 1 were polycristalline and the grain size was approximately 200 nm. Films were porous and the size of voids was approximately 100 nm. Between the SrTiO3 substrate and the YBa2Cu3Ox film a densly grown crystalline intermediate layer approximately 150 nm thick covered the SrTiO3 substrate. EDX microanalyses showed that the layer consisted of Sr, Ba and Ti, however, did not contain Y and Cu. Crystallites of the layer were carefully tilted in the microscope and diffraction patterns were obtained in five different poles for every crystallite. These patterns were consistent with the phase (Ba1-XSrx)2TiO4. The intermediate layer was most likely formed during the annealing at 900°C. Its formation can be understood as a diffusion of Ba from the amorphously deposited film into the substrate and diffusion of Sr from the substrate into the film. Between the intermediate layer and the surface of the film the film consisted of YBa2Cu3O7-x grains. Films prepared in process 1 had Tc(R=0) close to 90 K, however, critical currents were as low as jc = 104A/cm2 at 77 K.

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38

Pitschke, W., W. Bieger, G. Krabbes та U. Wiesner. "High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa". Powder Diffraction 10, № 3 (1995): 165–69. http://dx.doi.org/10.1017/s0885715600014652.

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The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

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39

Oh, B., Y. H. Choi, S. H. Moon, H. T. Kim та B. C. Min. "YBa2Cu3O7−δ/NdBa2Cu3O7−δ/YBa2Cu3O7−δ edge junctions and SQUIDS". Applied Physics Letters 69, № 15 (1996): 2288–90. http://dx.doi.org/10.1063/1.117536.

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40

Hirata, Kazuto, Kenji Iijima, Kazunuki Yamamoto, Katsuhiko Hayashi, Takahito Terashima, and Yoshichika Bando. "Growth and tunneling spectroscopy of YBa2Cu3O7−/insulator/YBa2Cu3O7−x junctions." Physica B: Condensed Matter 165-166 (August 1990): 1593–94. http://dx.doi.org/10.1016/s0921-4526(09)80382-7.

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41

Hendrix, Bryan C., Teruyoshi Abe, Janine C. Borofka, Pin-Chin Wang, and John K. Tien. "Hot Deformation of YBa2Cu3O7-delta and Composite YBa2Cu3O7-delta/Ag." Journal of the American Ceramic Society 76, no. 4 (1993): 1008–10. http://dx.doi.org/10.1111/j.1151-2916.1993.tb05327.x.

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42

SCHMITT, M., T. KLUGE, C. TOMÉ ROSA, et al. "PINNING FORCE DENSITY IN YBa2Cu3O7-FILMS AND YBa2Cu3O7/PrBa2Cu3O7-SUPERLATTICES." International Journal of Modern Physics B 07, no. 01n03 (1993): 135–38. http://dx.doi.org/10.1142/s0217979293000305.

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The in plane critical current density jc (B, Θ, T) of dc-sputtered YBa 2 Cu 3 O 7-films and YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices was measured in dependence of the angle Θ between the magnetic field [Formula: see text] and the [Formula: see text]-axis of the films in two orientations: 1. The current direction is parallel to the axis of rotation (i.e. [Formula: see text] always). 2. The current flows perpendicular to the axis of rotation (i. e. [Formula: see text]). For low temperatures we do not find any difference between the two current orientations, and the critical current density [Formula: see text] behaves like jc (B cos Θ, 0°). For higher temperatures the two cases differ from each other for Θ near to the maxima in jc at 90° and 270° for the YBa 2 Cu 3 O 7-films whereas for YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices we hardly find any change for both experimental setups. We compare the behaviour of the experimental results for the two orientations for the YBa 2 Cu 3 O 7-films and YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices and discuss the temperature dependence of the intrinsic pinning force density.

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43

Fujimoto, E., H. Sato, T. Yamada та H. Akoh. "All YBa2Cu3O7−δ trilayer junctions with YBa2Cu3O7−δ wiring layers". Applied Physics Letters 80, № 21 (2002): 3985–87. http://dx.doi.org/10.1063/1.1481765.

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44

Stölzel, C., M. Siegel, G. Adrian та ін. "Transport properties of YBa2Cu3O7−δ/Y0.3Pr0.7Ba2Cu3O7−δ/YBa2Cu3O7−δJosephson junctions". Applied Physics Letters 63, № 21 (1993): 2970–72. http://dx.doi.org/10.1063/1.110289.

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45

Myers, K. E., K. Char, M. S. Colclough та T. H. Geballe. "Noise characteristics of YBa2Cu3O7−δ /CaRuO3/YBa2Cu3O7−δ Josephson junctions". Applied Physics Letters 64, № 6 (1994): 788–90. http://dx.doi.org/10.1063/1.111014.

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46

Lee, Soon-Gul, Keunseop Park, Yong Ki Park, Yong Ho Lee, Hyuk Chan Kwon та Jong Chul Park. "YBa2Cu3O7−δ/PrBa2Cu3O7−δ/YBa2Cu3O7−δ edge junction dc SQUIDs". Physica B: Condensed Matter 194-196 (лютий 1994): 99–100. http://dx.doi.org/10.1016/0921-4526(94)90379-4.

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47

Pysarenko, Serhiy, Alexey V. Pan, and Shi Xue Dou. "Constrains of Super-Current Flow in YBCO Coated Conductors." Materials Science Forum 654-656 (June 2010): 1704–7. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1704.

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High temperature superconducting YBa2Cu3O7 films have been prepared by pulsed laser deposition on top of single crystal substrates and metallic templates. Films have been investigated in order to determine the influence of microstructural peculiarities on the critical current density. It has been found that there is an inherent mechanism limiting the superconductive current flow in YBa2Cu3O7 film deposited on metallic template. This mechanism is associated with YBa2Cu3O7 film architecture, fabrication procedure and following low temperature usage.

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48

Dean, K. A., D. B. Buchholz, L. D. Marks та ін. "YBa2Cu3O7−δ on MgO films grown by pulsed organometallic beam epitaxy and a grain boundary junction application". Journal of Materials Research 10, № 11 (1995): 2700–2707. http://dx.doi.org/10.1557/jmr.1995.2700.

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MgO films and YBa2Cu3O7−δ/MgO multilayer films were developed with the pulsed organometallic beam epitaxy (POMBE) growth technique, and grain boundary junctions were fabricated from the films to demonstrate the utility of the multilayers. High-quality MgO films were grown on LaAlO3 substrates by POMBE using a Mg(dpm)2 precursor. MgO crystallinity, as assessed by x-ray diffraction rocking curves, improved with the use of CuOx or YBa2Cu3O7−δ buffer layers. YBa2Cu3O7−δ films grown on the MgO layer by POMBE exhibited a Tc0 of 83 K and a Jc (12 K) exceeding 106 A/cm2 for applied magnetic fields up to 3 × 104 G. Grain boundary junctions were formed by growing YBa2Cu3O7−δ on MgO films that had been pretreated with a simple sputtering technique. This sputtering induces a controlled, 45°grain boundary in subsequently deposited YBa2Cu3O7−δ films. The resulting boundary showed weak-link current-voltage behavior and an IcRn product of 52 μV at 10 K, demonstrating that sputter-induced grain boundary junctions are compatible with multilayer technology.

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49

Hirao, Masahiko, Tsuyoshi Uda, and Yoshimasa Murayama. "Electronic structure of YBa2Cu3O6 and YBa2Cu3O7 by density-functional pseudopotential band calculation." Physica C: Superconductivity 185-189 (December 1991): 1551–52. http://dx.doi.org/10.1016/0921-4534(91)90902-b.

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50

Eckert, D., A. Junod, A. Bezinge, T. Graf, and J. Muller. "Low-temperature specific heat of YBa2Cu3O7, YBa2Cu3O6, Y2BaCuO5, YBa3Cu2O7, BaCuO2, and CuO." Journal of Low Temperature Physics 73, no. 3-4 (1988): 241–54. http://dx.doi.org/10.1007/bf00681980.

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