Lattice vibration of Sr3TaGa3Si2O14 single crystal

Based on the space group theory, the normal vibrational modes of Sr3TaGa3Si2O14 (STGS) single crystal were predicted, and the Raman scattering intensities of non-polar and polar modes were calculated. The lattice vibration modes of STGS crystal were studied by density functional theory (DFT) using the Dmol3 module in Material Studio program package. A Sr3TaGa2SiO12 cluster was constructed, and its vibrational frequencies were calculated using GAUSSIAN98 quantum chemistry suite. Excellent agreement has been achieved between theory prediction and Raman spectroscopy experiment results. The layer structure of STGS crystal was identified, and its small anisotropy and piezoelectric modulus are ascribed to the weak distortion of decahedral unit. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.