Infrared active phonons in (Pr_2-xCe_x)CuO₄

We report infrared (IR) reflectivity measurements of polycrystals of the electron-doped superconductor (Pr2-xCex)CuO4. To understand the complex results, we utilized conducting ceramics in which the ab-plane phonons are screened, allowing observation of the A2u phonons (motion parallel to the c-axis). To obtain the Eu modes (motion in the ab-plane), we utilized small ab-plane single crystals. With these approaches, all of the allowed IR phonons (3A2u + 4Eu) were observed. We have assigned all of the modes to specific atomic motion. © 1990.