Transport behaviour due to structural control of cuprate composites YBa₂Cu₃O₇  –PrBa₂Cu₃O₇  

Abstract

Transport properties (electrical resistance and diamagnetism) of composites consisting of the cuprates YBa 2 Cu 3 O 7−δ and PrBa 2 Cu 3 O 7−δ (YBCO and PBCO) have been found to be considerably governed by the presence of the third phase Y 1−x Pr x Ba 2 Cu 3 O 7−δ (YPBCO) yielded around the grain boundaries of initial ingredients YBCO and PBCO. The transport characteristics are mainly featured by a drop of the resistivity ρ (its amplitude ρ) appearing at the onset temperature T c1 and a shoulder in the resistivity ρ-T curve. The resistivity drop describes the granular superconductivity of the existing YBCO grains, and the shoulder depicts emerging YPBCO. These two features correlate with each other, through the formation of YPBCO. Owing to the presence of YPBCO, the textural structure of the composites can easily be controlled by changing the sintering temperature T s and sintering time t s to yield a large variety of the electrical and diamagnetic behaviours.

Critical current density in (YBa2Cu3O7−δ)1−–(PrBa2Cu3O7−δ) melt-textured composites

“…x relation in this system: hole filling [5], pair breaking [6], hole location [7] and percolation [8][9][10].…”

“…The ionic size effect is coupled with the problem of how Pr doping deteriorates the superconductor state and consequently the superconductor/insulator transition [8][9][10]. It is believed that the deterioration is produced with the localization of holes around the Pr ion, occurring due to the hybridization between Pr-4f orbital and neighboring O-2p in the CuO 2 plane.…”

“…x Pr x Ba 2 Cu 3 O 7- polycrystalline samplesand composites consisting of YBa 2 Cu 3 O 7- and PrBa 2 Cu 3 O 7- [8][9][10]. The results were described as a mixed crystalline solid solution consisting of two kinds of crystal unit cells Y-123 and Pr-123.…”

“…The results were described as a mixed crystalline solid solution consisting of two kinds of crystal unit cells Y-123 and Pr-123. In this model, the system is regarded as a 2D site-percolation structure built along the ab-plane with structural resolutions on nano-and micron-metre scales [8][9][10].…”

“…It is important to point out that the depression of superconductivity by Pr ion for (Y -Pr) -123 and YPr -123 samples occurred at different scales, with structural resolutions on nano-and micron-metre scales [8][9][10], when considering the percolation model proposed by Yoshida et al In this model, the system is regarded as a 2D site-percolation structure built along the abplane with structural elements of Y-sited and Pr-sited crystal unit cells. Therefore, for the Y 0.95 Pr 0.05 Ba 2 Cu 3 O 7- sample, the depression must have occurred at a nano-metre scale while for the (YBa 2 Cu 3 O 7- ) 0.95 -(PrBa 2 Cu 3 O 7- ) 0.05 sample, it must have occurred at a micron-metre scale.…”