Staging model of the ordered stacking of vacancy layers and phase separation in layered NaxCoO2 (x0.71) single crystals

G. J. Shu,1 F.-T. Huang,1,2,3 M.-W. Chu,1 J.-Y. Lin,4 Patrick A. Lee,5 and F. C. Chou1,6,* 1Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan 2Taiwan International Graduate Program, Academia Sinica, Taipei 10115, Taiwan 3Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan 4Department of Physics, National Jiao-Tong University, Hsinchu 30076, Taiwan 5Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 6National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan Received 30 June 2009; published 28 July 2009