Vibrational properties ofBi2CuO4

We report both polarized Raman and unpolarized infrared-reflectivity spectra of ${\mathrm{Bi}}_2$ ${\mathrm{CuO}}_4$. $5A sub 1g—, 4$B_{2g}$, 6$E_g$, and 14 ir modes are clearly observed. The assignment of the observed Raman modes is given according to Cartesian symmetry coordinates and preliminary force-constant calculation on the basis of a rigid-ion model and by comparison with the spectra of the isostructural compound ${\mathrm{Bi}}_2$ ${\mathrm{PdO}}_4$. Similarities between vibrational properties of ${\mathrm{Bi}}_2$ ${\mathrm{CuO}}_4$ and high-$T_c$ superconducting oxides are discussed.