Raman scattering in LiCoO_2 single crystals and thin films

摘要

We report Raman scattering measurements for uniaxially textured and randomly oriented polycrystalline LiCoO_2 thin films as well as for LiCoO_2 and LiCo_(0.4)Al_(0.6)O_2 single crystals. For both the crystalline LiCoO_2 thin film samples and the single crystal LiCoO_2 samples, well defined phonon modes are observed at Raman shifts of 486 cm~(-1) and 596 cm~(-1) corresponding to the expected E_g and A_(1g) modes of the layered LiCoO_2 crystal structure with R3m symmetry. Upon al substitution ofr CO in LiCOO_2, the two phonon modes appear to shift to higher energy, but futher work is needed to clarify this point.