Raman spectra of the ordered vacancy compounds $CuIn3Se5$ and $CuGa3Se5$ Available to Purchase

The optical vibrational modes of the ordered vacancy compounds $CuIn3Se5$ and $CuGa3Se5$ have been obtained by Raman spectra at various temperatures. The totally symmetric $A1$ mode appears around 155 and $167 cm−1$ in $CuIn3Se5$ and $CuGa3Se5,$ respectively. All the lines observed, except the $B1$ modes, present a reduction in their frequencies by about 10% as compared to the corresponding values in the $CuInSe2$ and $CuGaSe2$ chalcopyrites. This is due to the presence in these compounds of an array of vacancies occupying particular sites in the cation sublattice. These tend to relax the stretching forces thus reducing the vibrational frequencies.