Crystal structure and lattice dynamics of Sr3Y(BO3)3

X-ray, Raman and infrared (IR) studies of the Sr3Y(BO3)3 (BOYS) single crystal grown by the Czochralski technique are presented. The crystal structure is trigonal, space group image (no. 148), and comprises six formula units in the unit cell with the hexagonal axes a=12.527(2) and c=9.280(2) Å. The assignment of the observed vibrational modes is proposed on the basis of lattice dynamics calculations. The unusual large bandwidth of the internal modes and the enhancement of the principal mean square thermal displacements for BO3 and Y(1) indicate that some type of disorder is present in the studied crystal.