Reflectance studies on single crystals of a series of rare-earth (R=Pr, Nd, Sm, Gd) copper oxides have been made to determine phonon frequencies as a function of rare-earth mass. The increase in interatomic force constants with increasing rare-earth mass, which leads to a reduction in the lattice parameters, increases the vibrational frequencies. In addition, the change from the T-phase La2CuO4 to the T<-phase R2CuO4 crystal structure causes changes in the phonon frequencies that are due both to the changing lattice parameters and to the relocation of the apical oxygen atoms.
ASJC Scopus subject areas
- Condensed Matter Physics