Year: 2006
Type: article
Abstract: Raman spectroscopy measurements have been performed on $\ensuremath{\alpha}$-, $\ensuremath{\beta}$-, and $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Na}}_{x}\mathrm{Co}{\mathrm{O}}_{2}$ phases differing in their stacking of $\mathrm{Co}{\mathrm{O}}_{6}$ octahedra along the $c$-axis direction. The results demonstrate that, in general, there are five Raman active phonons for $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Na}}_{0.75}\mathrm{Co}{\mathrm{O}}_{2}$, two Raman active phonons for $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Na}\mathrm{Co}{\mathrm{O}}_{2}$, and three Raman peaks for $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Na}}_{0.6}\mathrm{Co}{\mathrm{O}}_{2}$. We have also performed Raman-scattering measurements on several $\ensuremath{\gamma}\text{\ensuremath{-}}{(\mathrm{Ca},\mathrm{Sr})}_{x}\mathrm{Co}{\mathrm{O}}_{2}$ $(0.15\ensuremath{\leqslant}x\ensuremath{\leqslant}0.40)$ samples which show well-defined intercalated $\mathrm{Ca}∕\mathrm{Sr}$ ordering. The experimental data show that the intercalated cation ordering could result in visible alterations on Raman spectral structures. The observations of the spectral changes along with the variation of the $\mathrm{Co}{\mathrm{O}}_{6}$ stacking, as well as the intercalated $\mathrm{Sr}∕\mathrm{Ca}$ ordering suggest that the interlayer interaction plays an important role for understanding the phonon properties in this layered system.
Source: Physical Review B
Authors: H. X. Yang, Y. Xia, Y. G. Shi, H. F. Tian, R. J. Xiao, X. Liu, Y. L. Liu, J. Q. Li
Institutions: Chinese Academy of Sciences, Institute of Physics
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1556841081