Robust superconductivity against water corrosion in Ba <sub> 1− <i>x</i> </sub> K <i> <sub>x</sub> </i> Fe <sub>2</sub> As <sub>2</sub> bulks
Chang Tu, Chiheng Dong, Chao Yao, Peng Yang, Wenwen Guo, Qianjun Zhang, Dongliang Wang, Xianping Zhang, Yanwei Ma
Abstract
Abstract The degradation behavior of Ba x K 1− x Fe 2 As 2 bulks in deionized water has been investigated via magnetic and electrical measurements, x-ray diffraction (XRD) and microstructure analyses. It is found that the polycrystalline bulk suffers a small loss of superconductivity in the deionized water environment for the 1st 12 h. However, it remains stable through the latter 10 d of immersion. We conclude the corrosion mechanism and suggest that the barium carbonate crystals and the amorphous iron-oxide accumulated on the surface prevent further reaction between water and BaK122 compounds. This unique surface passivation effect of BaK122 bulks is beneficial for practical applications in humid atmospheres.