Infrared absorption spectra of Nd2-xCexCuO4 and R2CuO4 (R=Pr, Nd, Sm, and Gd) have been measured in the energy region between 250 and 800cm-1 at room temperature. For Nd2-xCexCuO4, it is found that the mode at about 350cm-1, which is the vibration of oxygen in the R-O layers along the a-axis, disappears both for the as-grown Nd2-xCexCuO4 of x≥0.08 and for the oxygen-reduced Nd2-xCexCuO4 of x≥0, and the disapperrance is correlated to the resistivity. For R2CuO4, it is found that the energy of the A2u symmetry mode, which is the oxygen vibration along the c-axis, increases by about 50cm-1 between Pr to Gd, and this fact suggests that the three dimennsional character increases in a sequence of Pr, Nd, Sm, and Gd.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering