Fine structure of optical spectra of [M2Cu2O3]m[CuO2]n crystals

The fine structure of the dielectric function in the spectral range 0.5-5.0 eV was studied in the [M2Cu2O3](m) [CuO2](n)-type crystals (where M = Ca, Sr, Y, Bi, rare earth elements) with the min values equal to 1/1,5/7, 7/10 and 9/13. The spectra were compared with those of structural analogues CuO, SrCuO2, Ca2CuO3 and LiCu3O3, containing similar Cu-structural units as well as with the spectra of other complex cuprates such as Y-123 and Bi-2212. The qualitative analysis of the spectra allowed one to reveal the correlation between optical features in the spectra of [M2Cu2O3](m) [CuO2](n), crystals and electronic excitations in corresponding structural units. On the basis of the correlation, the microstructure of various [M2Cu2O3](m)[CuO2](n) crystals was discussed. The general regularities in the fine structure of complex cuprates were described and the specific features for [M2Cu2O3](m)[CuO2](n), crystals were emphasized.