Phonon modes in Yb3Al5O12: Pressure dependence and model calculations

The Raman modes of Yb3Al5O12 single crystals and their pressure dependence up to 11 GPa are reported. The hydrostatic pressure was applied at room tem perature by using a diamond anvil cell (DAC). As the crystal volume decreas es all Raman peaks exhibit positive pressure slopes (partial derivative ome ga/partial derivativeP) which vary from 0.5 to 5.6 cm(-1)/GPa. The Raman pe ak at 362 cm(-1) is not split in this system, retaining a degenerate behavi or, which is opposite to that observed for other members of the rare earth garnets. Model calculations based on the Lennard-Jones potential provide th e phonon eigenvectors and their. frequencies which are in satisfactory agre ement with the experimental values.