Crystal structure of the new FeSe1-x superconductor
  The newly discovered superconductor FeSe1-x (x=0.08, Tconset=13.5 K at ambient pressure rising to 27 K at 1.48 GPa) exhibits a structural phase transition from tetragonal to orthorhombic below 70 K at ambient pressure - the crystal structure in the superconducting state shows remarkable similarities to that of the REFeAsO1-xFx (RE = rare earth) superconductors 
S. Margadonna, Y. Takabayashi, M. T. McDonald, K. Kasperkiewicz, Y.   Mizuguchi, Y. Takano, A. N. Fitch, E. Suard, and K. Pr...