- 作者: 王年豪 ; 高惠春
- 作者服務機構: 淡江大學化學系
- 中文摘要: By means of the addition of Ba into the Bi-Ca-Sr-Cu-O 2122 system, a series of Bi/sub 2/CaSr/sub 2-x/Ba/sub x/Cu/sub 2/O/sub 8+.delta./(0.ltoreq.x.ltoreq.2) quinary metal oxides were prepared by the citrate route and by the conventional powder reaction method. The samples prepared by the former method have better properties than the latter. It was found that.delta. was not equal to zero for all of them and that it increased with decreasing Tc. Two phases were identified in the oxides containing all five metal elements. One is the Bi-Ca-Sr-Cu-O 2122 phase, the other is a new insulating phase which probably contains Bi-Ca-Ba-Cu-O with undetermined stoichiometry. Superconductivity was found in those samples for which x.ltoreq.1.50 with their Tc onsets between 93-78 K by resistivity measurements. Superconductivity decreased monotonically with increasing x. However, residual resistance was found in those samples for which 1.00.ltoreq.x.ltoreq.1.50. The Meissner effect appears in the samples where x.ltoreq.1.00 with Tc onsets between 88-80 K. For x=1.75 and 2.00, the samples were semiconductors with resistivities of 6.66*10/sup 2/ and 6.96*10/sup 3/.OMEGA..bcdot.cm at 290K, and activation energies of 0.109, and 0.298eV, respectively.
- 英文摘要: --
- 中文關鍵字: High-Tc Superconductor; Bi-Ca-Sr-Cu-O System; Ba Substitution; Citrate Precursor; Iodometric Titration; X-Ray Diffraction; Resistivity; Meissner Effect
- 英文關鍵字: 高溫超導體;鉍-鈣-鍶-銅-氧系統;鋇取代;檸檬酸先質;碘量滴定法;X-光繞射;電阻