## 抄録

The effect of excess Ca_{2}PbO_{4} on the superconducting properties of Bi_{1.7}Pb_{0.3}Sr_{2}Ca_{2}Cu_{3 }O_{y}B_{x} (B ≡ Ca_{2} PbO_{4}) is investigated through X-ray diffraction, resistivity and a.c. magnetic susceptibility measurements. The Xpray diffraction results show that the volume friction of the low T_{c} (221s) phase decreases and that of (2223) phase increases with the addition of Ca_{2}PbO_{4}. For x = 0.6 and 1.5, only the (2223) phase exists. At higher Ca_{2}PbO_{4} concentrations, i.e. for x = 3.0, the low T_{c} phase again appears along with the high T_{c} phase. Diffraction peaks appear at d = 2.02, 2.814 and 2.85, which are characteristic peaks of Ca_{2}PbO_{4}, and their intensities increase with increasing x, indicating that Ca_{2}PbO_{4} exists in the lattice in the same form. However, the T_{c}(0) values decreased gradually from 107 to 98 K with increasing Ca_{2}PbO_{4} concentration. Compared with the undoped sample, the width of the transition δT_{c} is broad for impurity-added samples and reaches a maximum value for x = 3.0. Pure and Ca_{2}PbO_{4}-doped samples showed two peaks in ξ″ vs. T curves and two steps in ξ′ vs. T curves. The first peak is close to the transition temperature and corresponds to the midpoint of the first step in the ξ′ curve. The second peak appears below 98 K and this peak maximum corresponds to the midpoint of the second step. The position of both sets of peaks remained almost the same up to x = 1.5 and shifted towards lower temperatures thereafter. The role of Ca_{2}PbO_{4} in the growth of the (2223) phase and the mechanism of energy loss are discussed.

本文言語 | English |
---|---|

ページ（範囲） | 312-317 |

ページ数 | 6 |

ジャーナル | Materials Science and Engineering B |

巻 | 20 |

号 | 3 |

DOI | |

出版ステータス | Published - 1993 7月 30 |

外部発表 | はい |

## ASJC Scopus subject areas

- 材料科学（全般）
- 凝縮系物理学
- 材料力学
- 機械工学

## フィンガープリント

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