Raman and infrared spectroscopic investigations on the crystal structure and phonon modes of LaYbO₃ceramics

LaYbO 3 is a highly distorted perovskite with orthorhombic structure. However, its exact space group has been a matter of debate. Both the polar Pna 2 1 and the centrosymmetric Pnma space groups, with Z = 4, have been proposed to describe its structure at room temperature. In this work we present optical spectroscopic investigations by Raman scattering and infrared reflectivity of LaYbO 3 ceramics sintered at 1600 °C. The results allowed us to propose a new centrosymmetric Cmcm space group for this compound, and to show which phonons give the main contributions to its dielectric constant and quality factor at microwave frequencies.