Amorphous FeAs-free SmFeAsO1?xFx using low temperature sintering with slow cooling

11th European Conference on Applied Superconductivity

Fujioka, Masaya^1 ; Denholme, Saleem J.^1 ; Okazaki, Hiroyuki^1 ; Deguchi, Keita^1,2 ; Demura, Satoshi^1,2 ; Hara, Hiroshi^1,2 ; Takeya, Hiroyuki^1 ; Yamaguchi, Takahide^1 ; Kumakura, Hiroaki^1,2 ; Takano, Yoshihiko^1,2

National Institute for Materials Science, Ibaraki, Tsukuba

305-0047, Japan^1

University of Tsukuba, Ibaraki, Tsukuba, 305-0001, Japan^2

关键词: Fluorine concentrations;    Impurity phasis;    Low temperature synthesis;    Low-temperature sintering;    Normal state;    Oxygen site;    Slow cooling;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/507/1/012015/pdf
DOI  :  10.1088/1742-6596/507/1/012015

来源: IOP

【 摘 要 】

We obtained the highest superconducting transition temperature of SmFeAsO1-xFxat 58.1 K by using low temperature synthesis with slow cooling. We found that the low temperature sintering suppresses the formation of amorphous FeAs, and the slow cooling introduces a high level of fluorine into oxygen site. By using this method, impurity phases are not formed up to x 0.16, and they gradually increase above x 0.16. However, the resistivity of the normal state continues to decrease and Tconset gradually increases with increasing fluorine concentration even when x > 0.16. Therefore, it is suggested that the fluorine is gradually introduced into oxygen site above x 0.16.