In situ visible Raman spectroscopic study of phase change in LiCoO2 film by laser irradiation

A phase change in LiCoO2/Co films in a spot of 1 μm diameter has been investigated under ambient conditions using 514.5 nm radiation by laser Raman spectroscopy. Laser irradiation resulted in a remarkable phase change of the film from hexagonal to cubic spinel, forming a lithium deficient phase Li1−xCoO2, which was enhanced with laser power. Based on comparative Raman studies, incorporation of cobalt atoms from the Co substrate by the local heating effect of laser irradiation has been suggested for the phase change. The in situ tool is expected to be useful for applications in control of micro-structure of cathode films for micro-batteries and micro-structural analysis.