1303.1309 (Masaya Fujioka et al.)

α-FeAs-free SmFeAsO1-xFx by low temperature sintering with slow
cooling    [PDF]

Masaya Fujioka, Saleem James Denholme, Toshinori Ozaki, Hiroyuki Okazaki, Keita Deguchi, Satoshi Demura, Hiroshi Hara, Tohru Watanabe, Hiroyuki Takeya, Takahide Yamaguchi, Hiroaki Kumakura, Yoshihiko Takano

We obtained amorphous-FeAs-free SmFeAsO1-xFx using a low temperature sintering with slow cooling. SmFeAsO1-xFx is sintered at 980 {\deg}C for 40 hours and cooled slowly at the rate of 5 {\deg}C /h to 600 {\deg}C. The low temperature sintering suppresses the formation of amorphous FeAs, and the slow cooling introduces much fluorine into SmFeAsO1-xFx. The superconductivity of this sample appears at 57.6 K. To study the change of fluorine concentration during the cooling process, samples are quenched by water at 950 {\deg}C, 900 {\deg}C, 850 {\deg}C, 800 {\deg}C, 750 {\deg}C and 700 {\deg}C. It is found that fluorine is substituted not only at the maximum heating temperature but also during the cooling process. The low temperature sintering with slow cooling is very effective to obtain a homogeneous SmFeAsO1-xFx with high fluorine concentration.

View original: http://arxiv.org/abs/1303.1309