Electronic properties of superconducting (YBa2Cu3O6.9)1−xAgx compounds

Pavuna, Davor; Berger, H.; Tholence, J.L.; Affronte, Marco; Sanjinés, R.; Dubas, Aleksander; Bugnon, Philippe; Vasey, F.

doi:10.1016/0921-4534(88)90310-3

Cited by 36 publications

(4 citation statements)

References 6 publications

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“…Ag in particular fills the intergranular spaces and improves both mechanical and electrical properties. A large number of studies [9][10][11][12] on the composites of YBa 2 Cu 3 O 7 (YBCO) and Ag have shown that Ag addition results in enhanced critical current density J c , reduced normal state resistivity and practically no change in the superconducting transition temperature T c .…”

Section: Introductionmentioning

confidence: 99%

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Behera

Mishra

2001

Supercond. Sci. Technol.

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Temperature-dependent electrical resistivity in a set of YBa 2 Cu 3 O 7 /Ag thick films prepared by reaction diffusion technique is analysed to estimate the extent of granularity in them. Percolative nature of charge transfer in the films was examined by studying the excess conductivity in the superconducting order parameter fluctuation (SCOPF) region (T T c ), the approach to zero-resistance state in the tail region, the current-controlled tailing of the resistivity transition near T c 0 (T c 0 < T < T c 0 ) and the current-voltage characteristics in the paracoherent regime (T < T c 0 ) with their associated exponents. The percolative current model was thus utilized to quantify granularity in the films of such parameters like the weak link resistivity across grain boundaries, current path lengthening factor arising due to grain misalignment, and due to voids and cracks. Evolution of these parameters with Ag content in the films indicates reduced structural defects (voids and cracks) at higher Ag concentrations. The result points to a mechanism of grain growth in the composites, which accounts for the improved grain growth with narrower grain size distribution in these systems as compared to that in Ag-free YBCO sintered material. These microstructural modifications cause lowering of percolation threshold from the value expected in a granular system where the grain size approaches to one of the system dimensions (the film thickness) making the conduction through grain boundary essentially two-dimensional.

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Section: Introductionmentioning

confidence: 99%

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Behera

Mishra

2001

Supercond. Sci. Technol.

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“…As shown in Table I, stabilization of 123 throughout the whole composite sample has been found by adopting one of the following approaches, including (1) replacement of the Ag source from pure Ag to Ag2O (samples 12 and 13), (2) reduction of the uniaxial pressure for sample compression from 150 to 15 MPa (sample 14), and (3) prolonged preannealing of the 123/Ag mixture powder in oxygen at temperatures above 400 °C before compression (samples [15][16][17][18]. As shown in Table I, stabilization of 123 throughout the whole composite sample has been found by adopting one of the following approaches, including (1) replacement of the Ag source from pure Ag to Ag2O (samples 12 and 13), (2) reduction of the uniaxial pressure for sample compression from 150 to 15 MPa (sample 14), and (3) prolonged preannealing of the 123/Ag mixture powder in oxygen at temperatures above 400 °C before compression (samples [15][16][17][18].…”

Section: Resultsmentioning

confidence: 99%

The stability of YBa₂Cu₃O_7−x in contact with silver

Lin

1994

J. Mater. Res.

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The stability of YBa2Cu3O7-x (the 123 compound) in contact with silver (Ag) at temperatures below 900 °C was investigated by conducting SEM and EDX analyses on 123 agglomerates that were enclosed in a dense Ag matrix and subjected to various thermal treatments. The stability of the 123 agglomerates was found to depend heavily on the oxygen content in the Ag matrix. In the case of insufficient oxygen content in Ag, the 123 agglomerates, which were as large as 150 fim thick, decomposed readily at temperatures above 500 °C. The complete decomposition process can be summarized as continuous extraction of Ba from the 123 oxide into the surrounding Ag matrix and is proposed to be driven by high mutual solubilities between Ag and Ba under the oxygen-lean condition. Prolonged preoxygenation of the (123 + Ag) mixture powders at temperatures above 400 °C prevents the occurrence of 123 decomposition in compacted samples during subsequent heat treatment, suggesting that the critical oxygen content in Ag for stabilizing the 123 compound to be no higher than 10"3 at. % (the oxygen saturation solubility at 400 °C). The findings may have implications for the processing of other Ba-containing high-Tc superconducting oxides as well.

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“…Since the discovery of new high-temperature superconductors, much attention has been paid to studying the role of silver in YBCO material [1][2][3][4][5][6][7][8][9][10][11]. These investigations have led to a significant improvement in the properties of YBCO ceramics.…”

Section: Introductionmentioning

confidence: 99%

Incorporation of silver in ceramics. Correlation between superconducting properties and microstructure

Nguyen-van-Huong¹,

Crampin²,

Laval³

et al. 1997

Supercond. Sci. Technol.

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The incorporation of silver in DyBCO ceramics was studied by EDX in TEM and correlated with the superconducting properties through R - T, I - V characteristics and critical current as a function of an external magnetic field. Two types of doping were performed: addition (A samples) and substitution (S samples) for . It was observed that for A samples, increases by K and is improved by a factor of 2. The influence of the applied field upon decreases slightly with x for A samples but the weak link behaviour remains. It was shown that silver does not enter in the 123 lattice. It slightly segregates at grain boundaries maintaining narrow junctions which are likely improve the coupling between grains, explaining the observed increase in . On the contrary, for S samples, is unchanged and the transition is wider. The effect of the magnetic field on increases with the doping level. Silver is found in the lattice, but the concentration is always lower than the nominal one and is limited to 0.12 for x = 0.4. This limited solubility leads to a deficiency in copper and consequently to noticeable ratio of second phases. Furthermore, a high segregation was observed at grain boundaries. This specific microstructure which produces wider junctions explains the decrease in .

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Electronic properties of superconducting (YBa2Cu3O6.9)1−xAgx compounds

Cited by 36 publications

References 6 publications

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

The stability of YBa₂Cu₃O_7−x in contact with silver

Incorporation of silver in ceramics. Correlation between superconducting properties and microstructure

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Electronic properties of superconducting (YBa2Cu3O6.9)1−xAgx compounds

Cited by 36 publications

References 6 publications

Granularity controlled percolative current conduction in YBa2Cu3O7/Ag composite thick films

Granularity controlled percolative current conduction in YBa2Cu3O7/Ag composite thick films

The stability of YBa2Cu3O7−x in contact with silver

Incorporation of silver in ceramics. Correlation between superconducting properties and microstructure

Contact Info

Product

Resources

About

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

Granularity controlled percolative current conduction in YBa₂Cu₃O₇/Ag composite thick films

The stability of YBa₂Cu₃O_7−x in contact with silver