Frequency shifts of infrared active phonon modes in orthorhombic Dy1−x YxMn2O5

A systematic investigation of infrared active phonon excitations in the orthorhombic Dy1-xYxMn2O5 with x=0, 0.2, 0.4, 0.6, 0.8, and 1 was carried out at room temperature. A detailed analysis towards the correlation between both local structural response and local lattice distortion has been undertaken. Frequency shifts of several phonons were observed, which strongly depends on the Y concentration and are likely to be associated with the electron-phonon coupling. A strong evidence for structural distortions of MnO6 and MnO5 has been observed in the high frequency range. The optical band gap has also been determined through optical conductivity and UV-visible absorption spectra, indicating semiconducting behavior of all members of the series Dy1-xYxMn2O5.