An investigation of the sodium patterning in Na(x)CoO(2) (0.5 <= x <= 1) by density functional theory methods

作者：Meng Ying S^*; Hinuma Yoyo; Ceder Gerbrand

来源：Journal of Chemical Physics, 2008, 128(10): 104708.

DOI：10.1063/1.2839292

Extensive experimental work has been carried out to characterize the stable Na-vacancy ordering patterns at various compositions of layered Na(x)CoO(2). However, contradictions and debates prevail in the literature, particularly at high Na concentrations x > 0.5. Understanding of the exotic electronic properties in this system requires a thorough understanding of the Na-vacancy structural orderings. Using density functional theory in the generalized gradient approximation (GGA), combined with a cluster expansion structure prediction algorithm we have found an intricate set of Na-vacancy ordered ground states in Na(x)CoO(2) (0.5 <= x <= 1). We demonstrate a newly predicted ordering pattern between 0.67 <= x <= 0.71. By comparing the first principles electronic structure methods within the GGA and GGA+U (Hubbard U correction) approximations, we demonstrate that at certain Na concentration the stable ordering is affected by charge localization on the Co layer through coupling between the Na and Co lattices.

• 出版日期2008-3-14