Superconductivity at 53.5 K in GdFeAsO1-delta
  Here we report the fabrication and superconductivity of the iron-based arsenic-oxide GdFeAsO1-delta compound with oxygen-deficiency, which has an onset resistivity transition temperature at 53.5 K. This material has a same crystal structure as the newly discovered high-Tc ReFeAsO1-delta family (Re = rare earth metal) and a further reduced crystal lattice, while the Tc starts to decrease compared with the SmFeAsO1-delta system. 
Jie Yang, Zheng-Cai Li, Wei Lu, Wei Yi, Xiao-Li Shen, Zhi-An Ren,   Guang-Can Che, Xiao-Li Dong, Li-Ling Sun, Fang Zhou, Zho...