Nonexistence of a substitutionalY1−xBi

Superconducting and Normal-State Properties of (Y1−x Bi x )Ba2Cu3O7−δ (x=0.00–0.30)

“…However, the zero-resistance temperature (T c zero ) decreased rapidly as the Bi content was increased resulting in the broadening of the superconducting-transition width ( T c ). The normalstate resistance versus temperature curves showed a metallic behavior for x ≤ 0.20 (consistent with the previous work [12]) and a semiconductor-like behavior for x = 0.25 and 0.30. All of our samples showed superconducting transition and this is contrary to previous report where transition temperature was not observed for x = 0.1 sample [11].…”

“…x = 0.01). This showed that Bi does not substitute Y even at very low substitution level (x = 0.1), consistent with the result by Cloots et al [12]. These impurities decreased T c zero and result in the broadening of the transition width.…”

“…The powders were heated at 900 • C for 48 h with several intermittent grindings and oven cooled. The powders were then pressed into pellets of 13 mm diameter and 2 mm thickness and heated at 900 • C (lower than the previous reports [11] and [12]) in air for another 24 h followed by furnace cooling to room temperature.…”

“…Nagata et al [11] reported effect of Bi in (Y 1−x Bi x )Ba 2 Cu 3 O 7−δ for x = 0 to 0.1 with sintering temperature 950 • C. Decomposition into more than two phases was reported in (Y 1−x Bi x )Ba 2 Cu 3 O 7−δ for low Bi content of x = 0.02 and no superconducting transition was observed for x = 0.1. Cloot et al [12] reported Bi substitution for x = 0 to 0.2 where Bi does not substitute Y in the YBCO structure. The samples were sintered at 870 • C and 930 • C. However, superconducting transition was observed at x = 0.2.…”