High pressure Raman study of Lu3Al5O12

In the present paper we study the effect of high hydrostatic pressure (up t o 16 GPa) on the Raman spectrum of Lu3Al5O12 Single crystals. Lu3Al5O12 bel ongs to the crystal family of rare earth garnets (Re3Al2(AlO4)(3), Re: Gd, Tb, Dy, Er,...). These materials crystallize with the body-centered cubic l attice and contain eight molecular units in the conventional unit cell. Gro up theory predicts 25 Raman active modes for these compounds, while experim entally 19 modes are observed for Lu3Al5O12. As the crystal volume decrease s all Raman peaks exhibit pressure coefficients varying from -0.1 to 5.0 cm (-1)/GPa. The phonon peak at approximate to 370 cm(-1) consists of two comp onents with symmetry A(1g) and T-2g, respectively. With increasing pressure a clear separation of the two components is induced. The Raman spectra did not show any evidence of phase transition in the pressure region under inv estigation.