Oxidation and reduction effects of successive superconducting transitions in ultra-fine YBa2Cu4O8 ceramics

29th International Symposium on Superconductivity

Hisada, Akihiko^1,2 ; Muranaka, Kie^2 ; Koyama, Kuniyuki^1,2 ; Magishi, Ko-Ichi^1,2 ; Saito, Takahito^2,3 ; Hagiwara, Makoto^4

Faculty of Science and Technology, Tokushima University, Tokushima

770-8506, Japan^1

Graduate School of Integrated Arts and Sciences, Tokushima University, Tokushima

770-8502, Japan^2

Institute of Liberal Arts and Sciences, Tokushima University, Tokushima

770-8502, Japan^3

Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Kyoto

606-8585, Japan^4

关键词: Grain surface;    Oxidation and reduction;    Reduction treatment;    Resistivity measurement;    Sintering process;    Submicron grains;    Superconducting transitions;    Zero resistivity;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012010/pdf
DOI  :  10.1088/1742-6596/871/1/012010

来源: IOP

【 摘 要 】

We investigated the effects of oxidation and reduction on the successive superconducting transition in a ceramic material composed of YBa2Cu4O8(Y124) submicron grains by linear and non-linear resistivity measurements. This material shows two-step superconducting transition and the lower one is identified as an inter-grain ordering. A sintering process fuses and joins the adjacent grains, so the lower transition was suppressed with increasing sintered time. Although Y124 is a stoichiometric ceramic, a reduction treatment suppressed the temperature of zero resistivity and broadened the non-linear resistivity peak. This suggests an oxygen vacancy was induced on the grain surface.