Showing papers by "Qian Zhang published in 1988"
TL;DR: In this paper, measurements of x-ray diffraction, the temperature dependence of the dc resistance and the ac susceptibility have been performed for the single-phase 3D-metal doping systems YBa2 Cu3−x Mx Oy (M=Fe, Co, and Ni; x=0.025, 0.05,0.075, 0,0,1.25,0.,0.10, 0.,1.15,0; 0.20 for Ni and Co and 0.50 for Fe).
Abstract: The measurements of x‐ray diffraction, the temperature dependence of the dc resistance and the ac susceptibility have been performed for the single‐phase 3D‐metal doping systems YBa2 Cu3−x Mx Oy (M=Fe, Co, and Ni; x=0.025, 0.05, 0.075, 0.10, 0.25, and 0.50 for Ni and Co and 0.05, 0.075, 0.10, 0.15, and 0.20 for Fe). With an increase of impurity content, two structural transitions were observed for the Co and Fe dopants but only one for the Ni dopant. The resistivity in the normal state changes from metallic to semiconductinglike behavior and the depression of Tc is linear with the impurity concentration (x) when x<0.10. A weak Curie–Weiss type paramagnetism, which is enhanced with impurity content, exists in the samples studied. Incorporating other work on oxygen defects, we suggest that a change of oxygen content induced by doping was the dominant effect on superconductivity in these samples.
7 citations
TL;DR: In this article, a HREM study on the defects in the high-Tc superconductor YBaCuO discovered recently is reported, and it is found that there are large amounts of local lattice distortions, point defects, and misarrangements of Y or Ba atoms within the specimens observed.
Abstract: A HREM study on the defects in the high-Tc superconductor YBaCuO discovered recently is reported. It is found that there are large amounts of local lattice distortions, point defects, and misarrangements of Y or Ba atoms within the specimens observed. HREM images of grain boundaries and interfaces between the crystalline state and so-called intermediate-ordered state are obtained. It is found that the tripled period lattices are distorted, especially near the interfaces.
Es wird eine HREM-Untersuchung der Defekte in dem kurzlich entdecktem Hoch-Tc-Supraleiter YBaCuO durchgefuhrt. Es wird gefunden, das grose Anteile von lokalen Gitterverzerrungen, Punktdefekten und Fehlanordnungen von Y- oder Ba-Atomen in den beobachteten Proben exisiteren. Es werden HREM-Abbildungen von Korngrenzen und Grenzflachen zwischen kristallinem Zustand und sogenanntem Zwischenordnungszustand erhalten. Es wird gefunden, das die dreifach-periodischen Gitter verzerrt sind, insbesondere in der Nahe der Grenzflachen.
2 citations