Sodium ion ordering and vacancy cluster formation in NaxCoO2 (x=0.71 and 0.84) single crystals by synchrotron X-Ray diffraction.
In the rich phase diagram of NaxCoO2, x=0.71 enjoys special stability and is called the Curie-Weiss metal due to its anomalous properties. Similarly, x=0.84 prepared from high temperature melt is a special end point beyond which the system phase separates. Using synchrotron x-ray diffraction on single crystals, we discovered sqrt[12]a and sqrt[13]a superlattice structures which we interpret as the ordering of Na (vacancy) clusters. These results lead to a picture of coexisting local moments and itinerant carriers and form the first step towards understanding the many anomalous properties of cobaltates.
Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan. fcchou@ntu.edu.tw
F C
FC
Chou
M -W
M-
Chu
G J
GJ
Shu
F-T
FT
Huang
Woei Wu
WW
Pai
H S
HS
Sheu
Patrick A
PA
Lee