Crystal structures of LaO1-xFxBiS2 (x~0.23, 0.46): effect of F doping on   distortion of Bi-S plane
  The crystal structures of superconducting LaO1-xFxBiS2 (x ~ 0.23, 0.46) were determined by single-crystal X-ray diffraction analysis. Their space group was P4/nmm. Distortion of the Bi-S plane changed when the F content was increased from 0.23 to 0.46, and a nearly flat Bi-S plane was formed at x ~ 0.46. Computational calculations supported this effect of F doping on distortion of Bi-S plane. LaO1-xFxBiS2 with higher F contents were computationally predicted to be thermodynamically more unstable under ambient pressure. We discussed the bonding, conductivities, and synthetic routes of LaO1-xFxBiS2. 
Akira Miura, Masanori Nagao, Takahiro Takei, Satoshi Watauchi, Isao   Tanaka, Nobuhiro Kumada
cond-mat.supr-con